







Surface area of a hemisphere 
20171028 

From Shaina: If the total surface area of a hemisphere be 36.22/7 cm then its radius will be 3 cm is it true or false Answered by Penny Nom. 





The surface area of a sphere 
20170917 

From penny: The surface area of a sphere is 1519.76cm. Taking 3.14 , find the radius of sphere Answered by Penny Nom. 





The surface area of a hexagonal pyramid 
20170616 

From Emilie: Hello, I need help with this question:
A pyramid has a regular hexagonal base with side lengths of 4 and a slant height of 6. Find the total area of the pyramid.
Thank you in advance if you can help me... Answered by Penny Nom. 





Corrosion inhibitor in a pipeline 
20160302 

From Edu: I have a 12 in pipeline and 5 miles long. I need to coat it with corrosion inhibitor how much chemical will I need Answered by Penny Nom. 





An algebra problem with a sphere 
20160229 

From Sania: If the number of square centimeters on the surface area of a sphere is equal to the number of cubic centimeters in its volume find its diameter Answered by Penny Nom. 





The surface area of a round bar 
20150606 

From chirag: Please tell me the formula for finding round bar surface in square inches/ mm Answered by Penny Nom. 





The surface area of a triangular prism 
20150603 

From Alex: Find the surface area of a triangular prism with Isoceles triangles and dimensions 4 feet by 6 feet Answered by Penny Nom. 





The surface area of a hemisphere 
20150505 

From Mandy: How can I show that the total surface are of any solid hemisphere is 75% of the area of the full sphere? Answered by Penny Nom. 





The surface area of a cut pipe 
20150427 

From ARUN: dear Sir,
please advise me , how to calculate the surface area of a pipe with diameter of 630 mm and thickness of 67 mm which is cut in a angle of 22.5 degree.
please show me how to calculate the surface area of the pipe which cut in an angle.
Thanking you. Answered by Harley Weston. 





The radius of a cylinder 
20150226 

From Rose: Hi. I want to know how to find the radius of cylinder.
When I have height (35cm) and area of the curved surface(880sq.cm).
I know the formula is 2πr(h+r). But I can't understand how to find it's radius.
Please help me. I really need your help. Answered by Penny Nom. 





A cuboid 
20141211 

From Nehal: Six cubes have a surface area of 24 cm2. They are joined together to male a cuboid.
What could the surface area of this cuboid be? There are two different answers. Answered by Penny Nom. 





A triangle on the surface of the Earth 
20140626 

From Christine: A, B and C are three towns, the bearing of B and C from A being 310 degrees and 220 degrees, and their distances from A are 510km and 700km respectively. Find the bearing of B from C to the nearest minute. Answered by Robert Dawson. 





Surface area 
20140502 

From vijay: If a square paper of side 25 cm is rolled to form a cylinder, then its curved surface area is Answered by Penny Nom. 





The surface area of a circular dome 
20140410 

From Shafiqah: Is this a dome's surface area formula??
{{2 × π r × h square units}}
Is the surface area of the floor for the dome is calculate too in this formula?
Thanks for answering. =) Answered by Robert Dawson and Penny Nom. 





The surface area of a rectangular prism 
20140408 

From Manraj: Find the surface area of a rectangular prism with dimensions 4, 5, and 7 units. Answered by Penny Nom. 





A cubical tank 
20140401 

From renzo: A cubical tank contains 2048 cubic ft of water when HALFFULL. Find the total area of the tank and the length of its diagonal Answered by Penny Nom. 





The surface area of a pyramid 
20130611 

From Sam: A right rectangular pyramid has a rectangular base measuring 18 cm by 32 cm. The height of the pyramid is 12 cm. What is the surface area? Answered by Penny Nom. 





The surface of a solid 
20130507 

From mustafa: I am doing a research paper on solid surface applications . Part of the project is to find four at least in our world today and explain what there purpose is. I really need help in this area because I've been searching the internet for where solid surface are used in our world today and I really can't find anything.. Thanking you in advance, mustafa Answered by Penny Nom. 





Frosting a three layer cake 
20121030 

From johnathan: Each layer of a 3 layer cake is a cylinder with height 7.5 cm. The bottom layer has diamegter 25 cm. The middle layer has dimegter 22.5 cm. The top layer has diameter 20 cm. The surface of the cke is frosted. What area of the cake is frosted. I get 1695.56 but the answer in the book is 2081.3 Answered by Penny Nom. 





Painting 400 drums 
20121005 

From Jordan: This cylinder is given:
Cylinder with a height of 84 cm and a diameter of 54 cm.
Question: The exterior of the drum (cylinder), except the base, is to be painted blue. calculate how many litres of paint will be needed to paint 400 drums if one litre of paint covers 8.8meters Squared.
Answer to nearest tenth of a litre. Answered by Harley Weston. 





\mbox 
20121005 

From Jordan: This cylinder is given:
Cylinder with a height of 84 cm and a diameter of 54 cm.
Question: The exterior of the drum (cylinder), except the base, is to be painted blue. calculate how many litres of paint will be needed to paint 400 drums if one litre of paint covers 8.8meters Squared.
Answer to nearest tenth of a litre. Answered by Harley Weston. 





The surface area of a dome 
20120606 

From sravya: how to calculate surface area of a dome if its base radius and height are known and neither it is hemisphere nor radius of sphere is known?? Answered by Walter Whiteley. 





The surface area of the tetrahedron 
20120404 

From youssef: how to find the total surface area of the tetrahedron ? Answered by Penny Nom. 





A cylindrical container 
20120214 

From KRIS: YOU ARE PaCKAGING 4 EQUAL SIZED PAINT CANS WITH A RADIUS 8CM AND A HEIGHT OF 20CM, IN A CIRCULAR CONTAINER.What is the surface area of the packing container? Answered by Penny Nom. 





Wallpapering a room 
20120208 

From jimmy: Ms. Frank is going to
wallpaper a living room with dimensions
24 feet long, 18 feet wide, and 8 feet
high. What surface area does Ms. Frank
plan to wallpaper? Answered by Penny Nom. 





A border around a flower garden 
20110828 

From jessica: A Landscaper, who just completed a rectangular flower garden
measuring 6 feet by 10 feet, orders 1 cubic yard of premixed
cement, all of which is to be used to create a border of uniform
width around the garden. if the border is to have a
depth of 3 inches, how wide will the border be?
( 1 cubic yard=27 cubic feet) Answered by Penny Nom. 





A cone with an oval as a base 
20110803 

From Emily: Hi, I was wondering how to calculate the surface area of a cone with an oval as a base (which I think is referred to as an elliptic cone or something like that). I have the both the maximum and minimum radius as well as the height, but I don't have a slant height and I'm not sure how to calculate it and then calculate surface area. I would really appreciate some help. Thanks! Answered by Robert Dawson. 





The surface area of a hemisphere 
20110529 

From Brenda: What is the surface area of a hemisphere with a radius of 2 inches? Answered by Penny Nom. 





The radius of a cylinder 
20110427 

From Jazmin: Hi, I don't understand how to find the radius in a cylinder with only the surface area (143.7) and the height (0.8)? I know that the formula is 2pir2+2pirh, but I don't see how to isolate the r? I appreciate your help. Answered by Penny Nom. 





The number of points on a line is equivalent to that of a surface 
20110324 

From Gary: I I was reading about how the number of points on a line is equivalent to that of a surface. This was done by taking any point on a line then taking alternating digits and making them as points on an x and y axis therefore points on a surface.The problem is as i see it if you just take a line then hold it over a surface you have just put the points on the line in a one to one correspondence with the points directly under it on the surface.Now you have all the rest of the surface which cannot be mapped onto the line since it is already used up.What am i missing? Answered by Penny Nom. 





Cutting the top off a conical tent 
20110222 

From tom: how far from the top must you cut a conical tent in order to cut the
cloth in half... Answered by Penny Nom. 





Tiling a swimming pool 
20110109 

From rustom: (a) Find the volume of water in swimming pool with vertical ends and sides
. The length measured at the water line is 50 ft. and the breadth is 20 ft. The
bottom of the swimming pool is a plane sloping gradually downward so that
the depth of the water at one end is 4 ft. and 8ft. at the other end.
(b) If the sides, ends, and bottom of the swimming pool are constructed of
tile blocks whose glaze surface dimensions are 3in by 6in. , and if the ends
and sides of the pool extend 2ft.above the water level, find the number of
blocks used if 1/20 of the surface area is covered by sealing material.
I got the (a) question but I don't know the (b) question which have the answer
of 16,136 blocks. I hope I can get the procedure for this, THANK YOU! Answered by Penny Nom. 





The outside surface area of a U shaped tube 
20100603 

From Adolfo: What is the formula for calculating the outside surface area of a U shaped tube? Answered by Robert Dawson. 





A cylindrical vessel with belled ends 
20100601 

From George: surface area of a vessel with a cylindrical length of 60 feet, a diameter of 10 feet, and with belled ends of 5foot radius Answered by Penny Nom. 





Painting a hemispheric dome 
20100509 

From Jone: If a hemispheric dome has a height of 20m and it take 5 gallons of paint
to paint the floor, how many gallons of pain are needed to paint the
inside of the dome? Answered by Penny Nom. 





Pyramids and parallelograms 
20100401 

From Vivi: Hi, my name is Vivi, and math teacher is giving a geometry test. I tend to forget how to find the surface area and volume of triangular pyramids and parallelograms. Do you have a way of remembering how to find the surface area? Answered by Harley Weston. 





Surface area of a dome 
20090916 

From Charlie: Why is the calculation for the surface area of a domed tank less than the surface area of a flat top tank.
Using domed tank formula 2*pi*r(r(rdome ht) works out to be less surface area than a flat top tank area formula pi*r x r,
Shouldn't the dome have more surface area than the flat surface ? Answered by Harley Weston. 





A spherical dome 
20090803 

From Eric: I have recently been asked to resurface a dome sculpture for my local council but i'm having problems working out the area. Here are the dimensions.
The height of the dome is 3m from the ground to the top of the arc. The arc itself from the ground rising up to the 3m point and back down, is 10m. The dome is 7m wide from one side to the other through the centre, at ground level.
I hope there is enough detail here. It's been a long time since i was in a maths class.
Thank you, hope to here from you soon! Answered by Stephen La Rocque. 





The surface area of a rectangular pyramid 
20090713 

From Shivani: What is the surface area of a rectangular pyramid with a length of 6 inches,
a width of 7 inches and a SLANT height of 4 inches. Answered by Penny Nom. 





The surface area of a fire pit 
20090630 

From eric: whatw is the square footage of the inside wall of a fire pit 2 feet deep and five feet in diameter? I need to estimate both the floor and wall square footage to order bricks. Answered by Robert Dawson and Harley Weston. 





The surface area of a tank 
20090625 

From Charles: I need to calculate the external wall and top sqft surface area of a tank 54ft od x 15ft high with a dome top 54ft od x 8ft high. Answered by Penny Nom. 





Constructing a cube 
20090408 

From Jill: you have a sheet of cardboard that measures 9ft x 6ft. To make the entire sheet into a closed box tht is a perfect cube, what would be the surface area of the box? Answered by Robert Dawson. 





Surface area of a cube 
20090222 

From JOHNNIER: determine the surface area of a cube with volume 125 mm3, thank u very much Answered by Penny Nom. 





Surface area and scale factors 
20090221 

From tina: the surface area of a sphere is about 86 ft (2) find the surface area of a larger sphere that has a scale factor of 4 Answered by Penny Nom. 





The focal point of a parabolic surface 
20090220 

From kishore: how to find out the focal point of a parabolic surfaces Answered by Chris Langdon. 





The surface area of a cube and rectangular prism 
20090216 

From Mhiko: how to derived the total surface area of a cube and rectangular prism using geoboard?? Answered by Robert Dawson. 





How fast is the visible surface of the earth decreasing? 
20090124 

From Ray: A dive bomber loss altitude at a rate of 400 mph. How fast is the visible surface of the earth decreasing when the bomber is one mile high? Answered by Harley Weston. 





Surface area of an irregular shape 
20081215 

From Patrick: An irregular shaped object (lets say a gold nugget, not smooth with
pockets) can have its volume determined by comparing its mass in
water.
Is there any method or means or anything that could be used to
determine the surface area of this shape? Whether that be theoretical
mathematical formula to using a special infrared technique,etc...
The problem I foresee is that the component parts cannot be divided
into smaller geometric shapes. I would propose an answer although I
don't know if it is a good one: A liquid material that dries superthin, but
has a very specific and easily determined volume/mass is coated over
the object. Measure the mass difference between the beginning sample
of fluid and the mass after the object has been coated. Then determine
the surface area of the same mass of fluid in a geometric shape.
Is this feasible? Answered by Robert Dawson. 





A cereal box that has a volume of 12000cm^3 
20081124 

From William: Hi, I have this math question that says construct a ceral box that has a volume of 12000cm3 and the surface area of the box has to be between 3200cm2 and 400cm2, I found some dimensions that are 20 by 20 by 30 and it works, but when I attempt to make the box, or make a net I would need this hugh piece of paper/cardboard, which I don't have, is there an easier way to find different dimenshions so I dont need a hugh piece of paper to create a net easily? Because i've tried trial and error but it has taken to long and I cant find anything,else, thats resonable. Answered by Harley Weston. 





Scaling a logo 
20081020 

From Carl: Hello!
I hope that you can help me out here. I've been trying to figure this out for awhile now and can't come up with the answer logically.
I am a graphic designer by trade and need to figure out how large my client's logo should be.
The logo will need to be sized proportionally with the surface area of the page.
The logo will always be sized at 1.2938(w) x .75(h) on a letter size page (8.5 x 11).
My question is...
When you increase the size of the page (not always proportionally sized  dimensionally) how do figure out the NEW size of the logo.
I could have a page 20" x 40" or 30' x 4'... or ANY size really.
I believe I have the new surface area of the logo but can't find the new dimensions. Answered by Harley Weston. 





Exterior square footage of a dome 
20080819 

From Richard: I have to gold leaf a dome with a circumference of 29'. What would the exterior square footage be? Answered by Penny Nom. 





A right prism with a square base 
20080613 

From Malik: Question from Malik:
A company wants to alter the dimension of container. The new container is in the shape of right prism equivalent to the current one.
The current container has height of 12cm and square base. The new container has also square base, but in the dimension base is increased by 3cm and height is decreased by 5cm.
if the cardboard is used to manufacture the new container, what area of cardboard is used to make new container? Answered by Penny Nom. 





The surface area of a lemon 
20080611 

From Susan: How would I find the surface area of a lemon Answered by Harley Weston. 





The surface area of an "egg shaped" object 
20080528 

From Tom: How do you calculated the surface area of an "egg shaped" object (ovoid) ? Answered by Harley Weston. 





The surface area of a cube 
20080524 

From cailtlin: hi.. if the surface area of a cube is 384 cm^2, how could i find the length of one edge? thank you Answered by Penny Nom. 





The surface area of a tank 
20080509 

From jack: i'm looking for the square footage of a tank that is 10'diameter x 23'high,floor,ceiling and walls Answered by Penny Nom. 





Surface area 
20080501 

From John: I am working with concrete and need some assistance please. I am trying to figure out what the surface space is for a one cubic foot that is four inches thick? Answered by Penny Nom. 





A rectangular prism 
20080331 

From Chanlie: i need need to find a rectangular prism with a total surface area of 210 units. Answered by Penny Nom. 





The surface area of a cube and a cylinder 
20080316 

From sunday: I'm doing a unit assessment, and there is something I don't understand. Now in my textbook, it says that surface area for a cube is different from a cylinder. Surface area for a cylinder has two numbers, but surface area for a cube has 3 or more numbers. And plus, I can't figure out the volume for a cube because it only shows volume for a cylinder. So how do I get this right? Answered by Harley Weston. 





The surface area of an ellipse 
20080225 

From paritosh: how is the surface area of a elliptical dome be calculated when the two diameters are 55 metres and 35 metres and the height of the structure is 13.4 mts? Answered by Harley Weston. 





The surface area of a hemisphere 
20080114 

From Nicholas: the surface area of a hemisphere is 1062 cm2. What is the radius? Answered by Penny Nom. 





The surface area of the rectangular solid 
20071230 

From Sara: For my math homework i found the volume of a rectangular solid whose deminsions were in feet and the numbers were 10 by 20 by 30
10 = hight
20 = short side base
30 = long side base
and now i have to find the surface area of the rectangular solid....
i know how to do this but i can't get the right answer
it should be 2,200 ft squared but i keep getting 13,00 feet squared Answered by Penny Nom. 





Square yards 
20071130 

From Chad: I need to convert 4,599 Cubic Yards to Square yards. The thickness is 10 inches. Is there a formula for this conversion.
Thanks, Answered by Penny Nom. 





Changing units and sizes of things 
20071108 

From Carol: volume of cube = 216 cubic inches how do I calculate cubic feet and calculate its surface area in square feet.
a rectangular box has dimensions of 3 x 6 x 15 how do I calculate surface area in square yards and calculate volume in cubic inches. if I double the dimensions how does it affect the volume Answered by Stephen La Rocque. 





Measurements on a test tube 
20071030 

From Bruce: I figure that the surface area (SA) of a round bottom test tube
can be determined by the equation SA = 2pi*h*r
where r is the radius of the hemispheric bottom & column part, and
h is the height (h) at any point upwards from the bottommost portion
in the center of the tube.
I haven't been able to come up with an equation yet for the circumference
of such a test tube at any point upwards along the tube based
on the height in its center or on the distance along the outside
of the tube. Answered by Harley Weston. 





Surface area of an openended cone 
20071016 

From Lorne: What is the surface area of an open ended cone? Measured at 10' high,
16' diameter on the bottom and 2' diameter at the top. Answered by Stephen La Rocque. 





What is the total surface area of a cylinder? 
20071003 

From MATT: what is the total surface area of a cylinder with outside diameter 40 cm. thickness 10cm. and length 2m. Work in cm^2 Answered by Stephen La Rocque. 





Dividing the surface of a sphere 
20070930 

From Jaroslaw: Is there a formula or method to divide the surface area of a sphere into equal parts. For example; 36 equal parts, 60 equal parts or 92 equal parts and so forth. Answered by Chris Fisher and Stephen La Rocque. 





The surface area of a prism 
20070821 

From Iliyas: State the area of prism with logical proof? Answered by Penny Nom. 





Surface area of a coin 
20070705 

From Anne: Assuming both sides of a coin are identical, and a line tangent to the inner circle is 23 mm from edge to edge of the coin, and excluding the edge of the coin in the calculation, what is the surface area of the coin, in square millimetres? Answered by Stephen La Rocque. 





Circumscribing a golden cuboid with a sphere: surface areas 
20070614 

From Ainslie: A golden cuboid is defined as a rectangular prism whose length, width and height are in the ratio of phi : 1 : 1/phi.
Prove that the ratio of the Surface Areas of the golden cuboid to that of the sphere that circumscribes it is Phi : Pi. Answered by Stephen La Rocque. 





The surface area of a fire hose 
20070526 

From Vanessa: Why do we need to find the surface area of a fire hose (cylinder). Answered by Stephen La Rocque. 





Lateral area of a right cone 
20070517 

From Crystal: In my homework the question says the lateral area of a right cone is 226.08 cm cubed.
the slant hieght is 12 cm. Find the total surface area. How do I do that? Answered by Stephen La Rocque. 





Surface area of a cylinder 
20070513 

From Nina: if a cylinder is 23 ft high with a 12 ft radius, how do I find the surface area? Answered by Penny Nom. 





Area and a squarebased pyramid 
20070508 

From Nick: For a regular square pyramid with base perimeter 40 and slant height 50, what is the lateral and surface areas? Answered by Stephen La Rocque. 





The area of a pyramid 
20070428 

From Alexander: Total area of the plate required to fabricate a vessel(pyramid) the base is 0.6mx0.6m and height of 1.0m. Answered by Stephen La Rocque. 





Surface area of a sphere 
20070408 

From maria: I've read your solution to the problem of how to derive the formula of the surface area of the sphere.
But i've got a question that initially you demenstrate the area is apprximately equal to that of the lateral area of the cylinder.
Afterwards you simply say that the two areas are exactly equal. I'm very confused, how you connect your two statements together.
Can you explain to me how they are exactly equal? Your quick reply would be appreciated. Thanks for your help! Answered by Stephen La Rocque. 





Painting a pool 
20070325 

From vincent: Determine the total cost to put 2 coats of paint on the interior pool
and amount of water needed to fill pool
facts:
a gallon of paint will cover 50 square feet and cost $18.00
the pool will be filled when water is leveled 6" from the top of pool
there are approximately 7.48 gallons of water per cubic foot
Rectangle shape pool 36.0 long and 20.0 wide from top Answered by Stephen La Rocque. 





The Geosphere at the the Epcot Center park 
20070316 

From stephanie: The epcot center has a diameter of 265 ft the park needs to paint the park one can will cover 400 sq ft how many cans do they need ? Answered by Stephen La Rocque. 





Surface area of a triangular prism 
20070221 

From Katrina: What is the formula to finding the surface area of a triangular prism? Answered by Gabriel Potter. 





The surface area of a hexagonal prism 
20070219 

From Cari: How do you find the surface area of a hexagonal prism? Thank you. Answered by Penny Nom. 





Surface Area of a cone 
20070219 

From Cari: I am doing a math project. I am very confused on how to find the surface area of a cone. I have looked at other equtions but i still don't understand. How do you find the surface area of a cone that has a 15cm length and a 3.5cm radius? Answered by Penny Nom. 





The surface area of a dome 
20070211 

From chris: I need to figure the surface area of a dome which is 96" across and 48" tall. Could you help please? Thanks! Answered by Penny Nom and Melanie Tyrer. 





A cylinder has how many flat surfaces, vertices, and edges? 
20070109 

From Stacy: A cylinder has how many flat surfaces, vertices, and edges? Answered by Diane Hanson and Penny Nom. 





The surface area of a triangular prism? 
20061029 

From Amanda: What is the formula for the surface area of a triangular prism? Answered by Haley Ess. 





A dome with a square base 
20061017 

From Danielle: I need to know how to calculate the area of a dome that has a square base. In order to insulate the room I need to find the area of it but I am not sure how to do so because there is no formula for domes with square bases. Basically, the floor has 4 corners but the ceiling is dome shaped starting directly from the floor. Answered by Stephen La Rocque and Penny Nom. 





What is the radius of the sphere? 
20060517 

From Jimmy: The surface area and volume of a sphere are both equal to the product of 4digit whole numbers and pi. What is the radius of the sphere? Answered by Stephen La Rocque. 





Pythagorus and cone dimensions 
20060426 

From Glynnis: How do you find the measure of a side that is not the hypotenuse using the Pythagorean Theorem? Also, how do you figure the surface area and volume of a cone when the radius is 5 yards and the height is 8 yards? Answered by Stephen La Rocque. 





What is the surface area of a cone with a hemisphere on top? 
20060420 

From Jordan: How do you find the surface area of a cone with a hemisphere on top? The only information I have is the radius of the hemisphere, which is 4, and the total height, which is 7. Answered by Stephen La Rocque. 





The volume & surface area of a rectangular pyramid. 
20060227 

From Cheryl: My daughter is working on a math project & we are having a hard time finding the volume & surface area of a rectangular pyramid. Can you help us with this? Answered by Penny Nom. 





The height of a cylinder 
20060215 

From Autumn: the surface area of a cylinder with circumference 24pi cm. is 300pi cm^{2} . what is the height??? Answered by Penny Nom. 





How many flat surfaces does a cylinder have? 
20060214 

From Kimia: How many flat surfaces does a cylinder have? Answered by Stephen La Rocque. 





Surface areas 
20050511 

From Jessica: How can I demonstrate to my high school students the reason for the formulas for the surface area of a prism, right cylinder, and regular pyramid, and right cone? Answered by Penny Nom. 





Volume and surface area of a prism 
20050429 

From Melissa: Can you please tell me if the volume and surface area of a prism can ever be the same? Could you please explain why or why not. Answered by Walter Whiteley. 





The surface area of a pyramid 
20040619 

From Jason: I was wondering how to find the area of a pyramid when you donít know the height of the face but the height of the Pyramids highest point? Answered by Penny Nom. 





Surface area of a cylinder 
20040417 

From Kathryn: How do you find the radius of a cylinder when you are given only the surface area and the height of the cylinder? Answered by Penny Nom. 





Surface area of a sphere 
20030723 

From Rob: I have a shere with a circumference of 12 feet. What is the total surface area of the shere in square feet and how did you find it? Answered by Penny Nom. 





The surface area of a cube 
20030407 

From Sarah: if the volume of a cube is 64 cm, then what's the total surface area? I also want to know how to show my work. Answered by Penny Nom. 





Doubling the size of an object 
20030401 

From Dave: If I have a known surface area and volume of an unknown object and I want to double the size of the object, how do I find the new area and volume? Answered by Walter Whiteley. 





Surface area of a sphere 
20030311 

From Kim: a sphere has a surface area of 128 pi sq. units. What is its exact radius? formula is 4 pi r^{2} I believe but how do I get radius Answered by Penny Nom. 





A triangular prism 
20020428 

From A student: Need the formula for the surface area of a triangular prisim? Answered by Penny Nom. 





Intersection of perpendicular cylindrical surfaces 
20010731 

From Charlie: Please consider two right circular cylinders, perpendicular one to the other, and of unlike radii in a 3 dimensional Cartesian space with mutually perpendicular x,y,z axes. If one cylinder is centered on the y axis with radius ra, and the other on the z axis with radius rb, then the expression for the first surface would be x^{2} + z^{2} = ra^{2}, y = any number. Likewise, the second cylinder's surface would be x^{2} + y^{2} = rb^{2}, z = any number. It is my intent to define the curve at the intersection of these two cylindrical surfaces. From sketching the conditions it appears that this intersection resembles an ellipse folded about its minor axis. Answered by Chris Fisher. 





Volume and surface area of a cylinder and a triangular prism 
20010331 

From Kevin: I was wondering how do you find the volume and surface area of a cylinder and a triangular prism. Answered by Penny Nom. 





Surface area of a contact lens 
20000606 

From Evie Contreras: I would like to know how to calculate the surface area of a contact lens with a radius of 7mm? I know that the area of a circle is pi R squared, but a contact lens has a dome. Answered by Harley Weston. 





Surface area of a cylinder 
20000407 

From Jim Campbell: I am going to cover the outside of a shaft with some material. How do I figure the square inches of the outside surface of the shaft? Shaft is 6" in diameter and 24" long Answered by Harley Weston. 





Lining a cone 
20000406 

From Jim Campbell: I am not a student, I am trying to solve a business problem. The question. If I want to put a lining in a chute that is cone shaped, how do I calculate the size steel plate I need to do that. The cone is 10' in diameter at the top and has a 20" hole at the bottom. The total height of the chute is 8'. Answered by Harley Weston. 





Surface area of a sphere 
20000322 

From Gina Wilkie: How can I demonstrate to my middle school students the reason for the formula for the surface area of a sphere? Answered by Walter Whiteley and Chris Fisher. 





Surface area of a cone 
19990918 

From Frothy: I don't understand how to find the surface area of a cone. The height is 12cm and the radius is 5cm. Answered by Walter Whiteley. 





Platonic Solids Surface Area 
19981202 

From Rachel Bidwell: How do you find the surface area of the 5 platonic solids, when they each have a volume of one cubic inch Answered by Harley Weston. 





Surface Area 
19970430 

From Amber Nobile: The height of a cylinder is twice the diameter. Express the total surface area as a function of the height h. Answered by Harley Weston. 





Formulae for Surface Area. 
19970428 

From Gary Millward: I'm trying to help my son with his Math homework (Grade 10) and he has to find the surface area of a cone and rectangluar pyramid. We have the formulas for the volume of these solids, but can't seem to locate the formulas for surface area. Answered by Walter Whiteley. 





Nombres algebriques sur Q 
20020411 

From Un eleve: On sait que le corps des nombres algebriques sur Q est algebriquement clos. A priori partant d'un polynome f a coefficients algebriques sur Q on devrait pouvoir un trouver un polynome g a coefficients rationnels dont une partie des racines est constituee de racines du premier. yatil un algorithme qui permet qui permet le passage de f a g ? Answered by Claude Tardif. 

