







The volume o a hemisphere 
20180506 

From Sambox: When I have a hemisphere with a volume of 700Pi m^3 what is the radius? Answered by Penny Nom. 





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. 





A cone inscribed in a hemisphere 
20160807 

From anonymous: A cone is inscribed in a hemisphere. the slant height of the cone is 20cm. When cut along its slant height, the cone forms a sector of a circle.
find the angle of the sector, to the nearest 1 decimal place. 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 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 volume of a sphere 
20150430 

From Cassidy: How do you find the radius of a sphere that has volume 36pI? Answered by Penny Nom. 





Largest cone in a sphere 
20150115 

From Alfredo: What is the altitude of the largest circular cone that may be cut out from a sphere of radius 6 cm? Answered by Penny Nom. 





The volume and radius of a sphere 
20140427 

From grace: How do you find the radius of a sphere when all you know is the volume? Answered by Penny Nom. 





A cone inscribed in a sphere 
20140228 

From joel: how can I find the radius and the height of a cone INSCRIBED in a sphere, given the sphere having a radius of 6? ( note: the diameter of the cone is equal to its slanted height). Answered by Penny Nom. 





Covering a styrofoam ball with fabric 
20130911 

From Alice: I am trying to create a pattern in order to cover a styrofoam ball with fabric. The pattern needs to be done in such a way as to have only a center seam, rather than several vertical lines as in slicing a melon. Answered by Chris Fisher. 





The volume of a sphere 
20120818 

From Rohit: why isn't volume of a sphere = Area of a semicircle x the circumference.
i.e. if we revolve a semicircle around its axis we get a sphere Answered by Penny Nom. 





Water in a hemispherical bowl 
20120512 

From Jimmy: A bowl of water, being a hemisphere has a radius of 36cm.
Water is filled in the bowl and has depth of 18 cm.
Find the surface area of the water? Answered by Penny Nom. 





A rectangular block and a sphere 
20120202 

From snehal: a solid rectangular block of metal 49 cm. by 44cm. 18cm. is melted and formed into a solid sphere, find the radius of the sphere[22/7] Answered by Penny Nom. 





A cube inscribed in a sphere 
20120123 

From Gelo: What are the largest volume and total surface area of a cube that may be inscribed inside a sphere whose radius is 5 kilometers. Answered by Walter Whiteley. 





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 equation of a sphere 
20110416 

From kanika: equation of sphere and how to know its center Answered by Penny Nom. 





A conical container and a spherical balloon 
20110406 

From Steven: Water is running out of a conical container 12 feet in diameter and 8 feet deep (vertex down) and filling a spherical balloon.
At the instant the depth of the water in the cone is 4 feet, the radius of the sphere is approximately 4 feet.
The rate of change of the depth of the water in the cone at the instant is approximately ______________ times the rate of change of the radius of the balloon. Answered by Penny Nom. 





The equation of a sphere 
20110209 

From kelly: what is the equation of a sphere if one of it's diameters has a giving end point of (4,4,4), (8,8,8)? Answered by Penny Nom. 





Packing spheres in a given region 
20100127 

From MISAEL: IN A VOLUME GENERATED BY TWO TRAPEZOIDS WITH DIFFERENT SURFACE AREAS BUT SHARING THE BOTTOM PLANE:
HOW CAN I CALCULATE THE "N" SPHERES WHICH THIS VOLUME CAN CONTAIN?
HOW CAN I CALCULATE THE VOLUME OF SPACES IN RELATIONSHIP WITH VOLUME OF SPHERES OR THE TOTAL VOLUME? Answered by Robert Dawson. 





A cone circumscribed about a given hemisphere 
20100119 

From Neven: The cone of smallest possible volume is circumscribed about a given hemisphere. What is the ratio of its height to the diameter of its base?
(G.F.Simmons, Calculus with Analytic Geometry, CH4 Applications of Derivatives) Answered by Chris Fisher. 





A triangle on a sphere 
20090907 

From Rohit: How do I find the angles of a triangle drawn on a sphere (spherical triangle)? Answered by Chris Fisher. 





Maximum Volume of a Cylinder Inscribed in a Sphere 
20090618 

From Jim: Hello I have a hard time finishing this question:
A right circular cylinder has to be designed to sit inside a sphere of radius 6 meters
so that each top and bottom of the cylinder touches the sphere along its complete
circular edge. What are the dimensions of the cylinder of max volume and what is the volume? Answered by Janice Cotcher. 





A large, hollow, ice cream cone 
20090403 

From Darah: A manufacturer is making a large, hollow, ice cream cone to serve as an ad for a local BaskinRobbins. The ice cream cone is made up of a cone with height 8 feet, topped by a hemisphere with radius 6 feet. How much ice cream could the hollow object hold? If a gallon is 0.13368 cubic feet, how many gallons does it hold? If 3 gallons of BaskinRobbins heavy cream chocolate blend weighs 24 pounds, how much would the ice cream cone weigh, excluding the weight of the construction material? Answered by Stephen La Rocque. 





The rate of change of the volume of a sphere 
20090325 

From Kaylin: why the rate of change of volume of a sphere is not constant even though dr/dt is constant? Answered by Walter Whiteley. 





How many ball bearings can you make from a cone? 
20090314 

From Vatsal: there is a sum in my maths book which states the following:
how many ball bearings of diameter 2.5 cm. can you get by
melting a solid metalic cone of radi. 20cm and a Hight of 5 meters?
how do i do this please tell me even the minute things like cancellatoins and where to
use = , ; or any such thing because Im a bit weak in maths Answered by Harley Weston. 





The floor area in a spherical space station 
20090214 

From Ed: I am writing a science fiction novel that involves a spherical space station with a
radius of 800 meters. Inside, artificial gravity allows parallel floors set 4 meters
apart. If you count the floor that has a radius of 800 meters as Floor 0, then the
next floor up (Floor +1) would by 4 meters above the surface of Floor 0. There
would then be Floor 1 4 meters down from Floor 0. This would continue until
you reach the top or bottom floor, where there is at least 4 meters but less than
8 meters to the top or bottom of the sphere. Obviously the top and bottom
floors would have the (same) smallest area, while Floor 0 would have about 2
million square feet.
My problem is figuring out the total area of all of the floors, or for that
matter, any particular floors or the total number of floors (the total of all the
+ floors, the  floors (these numbers will be the same) plus Floor 0.
Ed Answered by Penny Nom. 





Solid figures 
20090210 

From Rebecca: I need to know the names of solid figures. I have several pictures that I need to answer what type they are.
Thanks, Rebecca 3rd grade Answered by Penny Nom. 





A sphere in a cone 
20090210 

From Shubham: An upturned conical vessel of radius 6cm and height 8cm is completely
filled with water. A sphere is lowered in the conical vessel filled with
water and the size of sphere is such that it just touches the sides of
cone and is just immersed. What fraction of water overflows? Answered by Harley Weston. 





Segments of a sphere 
20090116 

From Herman: How do I solve for a segment of a sphere so that the orange peel or pie shaped section is converted to a flat surface with dimensions. I form large diameter domes, elliptical and sphere heads on a press. I enter the diameter say 30 feet with two segments above and below the equator and the total number of segment around the circumference at say 18 so the widest part of the pie shaped section will fit my press. How do I take the upper or lower course above or below the equator and figure the height of the orange peel shape, the chord length at top and bottom, and solve for the right angle at 2 degree increments down the arc length of the pieces so I can layout the flat plates prior to pressing. Thanks for your help. Answered by Robert Dawson. 





The volume and surface area of a sphere 
20090107 

From destini: the volume of a sphere is equal to its surface area. what is its radius Answered by Chris Fisher. 





A sphere in a can of water 
20081212 

From Meghan: A cylindrical can open at the top has (inside) base radius equal to 1.
The height of the can is greater than 2.
Imagine placing a steel sphere of radius less than 1 into the can, then pouring water into the can until the top of the sphere is just covered.
What should be the radius of the sphere so the volume of water used is as large as possible? Answered by Harley Weston. 





The volume is decreased by 25% 
20081117 

From Wanda: If the volume of a sphere is decreased by 25%, what is the new equation? Answered by Penny Nom. 





Melting ice on a hemisphere 
20081020 

From heather: The top of a silo is the shape of a hemishere of diameter 20 ft. if it is coated uniformly with a layer of ice, and if the thickness is decreasing at a rate of 1/4 in/hr, how fast is the volume of ice changing when the ice is 2 inches thick? Answered by Penny Nom. 





A sphere and hexagons 
20081019 

From Angela: A sphere is made of 112 hexagons. Each side measures 10 cm. The width of the border between each hexagon is 5 cm. What is the radius of the sphere? Answered by Chris Fisher and Walter Whiteley. 





The biggest right circular cone that can be inscribed in a sphere 
20080908 

From astrogirl: find the volume of the biggest right circular cone that can be inscribed in a sphere of radius a=3 Answered by Harley Weston. 





The diameter of a sphere 
20080615 

From Scott: The volume of a sphere is 6000cm cubed. What is the diameter of the sphere? Answered by Penny Nom. 





The radius of a sphere if you know the volume 
20080611 

From Cey: how to i find the radius of a sphere with a volume of 1000cm cubed using the formula v=4/3 pi r squared???????/ Answered by Penny Nom. 





A hemisphere and a cylinder 
20080518 

From Libby: A giant scoop, operated by a crane, is in the shape of a hemisphere of radius 24 inches. The scoop is filled with molten steel. The steel is then poured into a cylindrical storage tank with diameter 32 inches. How high will the molten steel rise?
I got the volume of the hemisphere and the volume of the cylinder, but I'm not exactly sure what to do next. Answered by Penny Nom. 





A net for a hemisphere 
20080506 

From Julie: how would you draw the net of a hemisphere? Answered by Walter Whiteley. 





The isoperimetric inequality 
20080421 

From Dutch: I'm searching for the proof that the sphere has the smallest volume of any figure and maximizes the volume of any figure. Answered by Chris Fisher. 





The height of a hemisphere 
20080325 

From Rebekah: what is the height of a hemisphere with a volume of 60 ft cubed? Answered by Stephen La Rocque. 





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. 





Smallest cone containing a 4cm radius inscribed sphere 
20071219 

From Eva: A sphere with a radius of 4cm is inscribed into a cone. Find the minimum volume of the cone. Answered by Stephen La Rocque. 





Ball bearings in an oil can 
20071203 

From Lisa: One hundred ball bearings with radius 5 mm are dropped into a cylindrical can, which is half full of oil.
The height of the cylinder is 20 cm and the radius is 8 cm.
By how much does the level of the oil rise? 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. 





Size of a sphere fitting inside a cone 
20070927 

From Juan: I am supposed to find the largest sphere that
will fit into a cone. I am assuming is a maximizing problem, but I am not sure
of what relation (between a cone and a sphere) to use. Answered by Penny Nom and Stephen La Rocque. 





A geodesic dome 
20070925 

From Roger: In my ScienceFiction series, I have a Dyson's Sphere tiled with
regular hexagons. The number of hexagons is over 300,000 and the
radius of the Sphere is roughly 80,000,000 miles. The actual size of the
Sphere and hexagons have been left flexible until I can come up with a
definite number of hexagons that would fit. My problem is the pattern of
hexagons which would fit within the sphere without leaving gaps or
overlapping.
My best guess has been to use four equilateral triangles composed of 78606
hexagons, (396 per edge) arranged around the sphere with six 'zippers' to
connect them and four 'caps' at the points, for a total of 316804 hexagons.
Given the fact that each Hex is the same size, does this seem plausible?
Is there some pattern formula I can use to play with these figures? Simple
divsion of areas will not work if the number derived will not fit into the
pattern to leave a perfectly tiled surface. Thank you. Answered by Chris Fisher. 





A cube in a sphere 
20070911 

From Justin: What percent of the volume of a cube is occupied by the largest possible sphere centered in that cube? Answered by Stephen la Rocque. 





The equation of a sphere 
20070811 

From isvarya: Find equation of the sphere with centre (1,4, 3) and radius 5
What is the intersection of this sphere with the xz plane? Answered by Harley Weston. 





Volume of a brewer's sphere 
20070604 

From Edward: A Brewer's Sphere that has a 9' Dia. Holds how much Brew? How many 40oz bottles will be needed to hold his batch of Brew? Answered by Stephen La Rocque. 





A cylinder inside a sphere 
20070425 

From Louise: i need to find the maximum volume of a cylinder that can fit inside a sphere of diamter 16cm Answered by Penny Nom. 





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. 





The volume of a hemisphere 
20070321 

From Sarah: How do you calculate the volume of a hemisphere?
Thanks. Answered by Penny Nom. 





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. 





Cut a given sphere by a plane 
20070314 

From Rory: Cut a given sphere by a plane so that the volumes of the two segments formed shall be in a given ratio.
Show that in modern notation, this leads to the cubic equation
m(r+x)^2(2rx)=n(rx)^2(2r+x)
where r is the radius of the sphere, x is the distance of the cutting plane from the centre of the sphere, and m/n < 1 is the given ratio.
Can you help me show the solution to this question. Thank you. 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. 





The volume of a sphere 
20070116 

From Anshul: How to prove or find the volume of sphere? Answered by Harley Weston. 





The radius of a hemisphere 
20061129 

From Emma: how do you calculate the radius of a hemisphere when you are given the volume? Answered by Stephen La Rocque. 





A spherical bowl 
20061126 

From Lynne: A spherical bowl of internal radius 15cm is partly filled with liquid. If the radius of the horizontal liquid surface is 12cm, calculate (taking the value of pi to be 3.142), the height of this liquid surface above the center of the bowl. Answered by Penny Nom. 





A sphere in a cube 
20061109 

From Lukas: Given a cube and a cross diagonal, what is the largest size sphere that fits in the cube and does not touch or intersect the cross diagonal? Answered by Steve La Rocque, Penny Nom and Walter Whiteley. 





The lower half of a sphere 
20060830 

From Yvette: I am interested in finding out how to represent the lower half of a sphere in the form of z=f(x,y) with r=2 and a centre point (3,1). Answered by Stephen La Rocque and Penny Nom. 





A cube inscribed in a sphere 
20060803 

From Glenn: Given the diameter of the sphere 10cm. find the largest cube inscribe in the sphere. Answered by Stephen La Rocque. 





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. 





The volume of water in a sphere shaped water tower 
20060514 

From Dan: I work in the water industry, providing automatic controls for water systems. I was wondering if there was a formula for calculating the volume of water in a sphere shaped water tower? With the use of a pressure gauge we know the elevation of zero water {the bottom of sphere) and the overflow elev. (near the top of sphere) I would like to calculate how many gallons are at any elevation in between. 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. 





Shapes 
20051112 

From Tonya and Hailey: MY THIRD GRADERS TEACHER HAS SENT HOME HOMEWORK ASKING FOR THEM TO FIND REALWORLD OBJECT IN MANY DIFFERENTS SHAPES A FEW HAVE US STUMPED Answered by Penny Nom. 





Volumes 
20051031 

From Diane: My name is Diane and I am a returning student to a vocational technical school.
As a reference point to see what I did/didn't remember from my HS math days, I was sent home with a 75 problem math packet. I was fine until I got to computing:
1. the volume of a cylinderis it pi r^{2} h?
2. the volume of a cone is it pi/3 r^{2} h?
3. the volume of a sphere I can't even hazard a guess.
Help my last classroom was 23 years ago, and I've forgotten far too much! Answered by Penny Nom. 





A cube in a sphere 
20051019 

From Damian: A sphere passes through the eight corners of a cube side 10cm. Find the volume of the sphere. Answered by Penny Nom. 





A melting ice sphere 
20050709 

From A student: A 2 meter diameter sphere of ice melts at 1.5 millimeters per minute. How many minutes will it take to fill up a hexagonal container measuring 1.5 meters on a side, and 0.8 meters deep? Answered by Penny Nom. 





The volume of a sphere. Why 4/3? 
20050530 

From Lauren: You know when you find the volume of sphere? I know the formula is V= 4/3 pi r^{3} but why do they use 4/3? Answered by Penny Nom. 





A torus and a sphere 
20050327 

From Tony: Is it possible to shrink a torus into a sphere? Answered by Andrei Volodin and Penny Nom. 





The volume of a sphere 
20050225 

From Stephanie: find the volume of a sphere that has a diameter of 12 cm.
please show me how to work this problem Answered by Penny Nom. 





The volume of a sphere 
20041130 

From Lyndsay: twenty cubic metres of air are pumped into a spherical hot air balloon with each given diameter: 1.0m; 2.0m; 3.0m; 4.0m; 5.0m;6.0m
a)calculate the new diameter, new suface area, and new volume of each balloon. Answered by Penny Nom. 





A copper sphere 
20040912 

From Irfan: The radius of a copper sphere is 3cm. If a wire of 0.4 diameter is drawn by melting it,what is the length of this wire? Answered by Penny Nom. 





A cube is inscribed inside a sphere 
20040818 

From A student: A cube is inscribed inside a sphere with radius sqrt8cm. Find the
(a) length of the cube
(b) volume of the space inside the sphere but outside the cube. Answered by Penny Nom. 





The volume of a sphere 
20040326 

From Mike: I was in class today and I learned how to calculate the volume of a sphere. I understood it easily but can't find the logic behind it. So here are my questions, in the formula why is the radius cubic and not squared? And what does 4/3 have to do with it? Answered by Penny Nom. 





Areas, perimeters and derivatives 
20040215 

From Geoff: A recent lecture in my calculus class led me to realize that the derivative of the area of a circle, with respect to the radius is equal to the circumfrence. This also holds true for the relationship between the volume of a sphere and the surface area of that sphere:
why do these hold true? why is it only for circular objects? Answered by Harley Weston. 





Noneuclidean geometry 
20031208 

From Geoffrey: How can you use noneuclidean geometry to navigate on a sphere? What geometers did work in this area? Answered by Chris Fisher. 





The general equation for a sphere 
20030911 

From Jaidev: Is there any general equation for a sphere? Answered by Penny Nom. 





A sphere inscribed in a cone 
20030810 

From A student: A sphere with radius 5cm is inscribed in a right circular cone 20 cm in height.find
(a) the base radius ,volume of the cone (b)volume of the shaded space( to 3 sig fig) 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. 





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. 





Volume of a sphere 
20020816 

From Rahul: How do i find the volume of a sphere without the knowledge of calculus? Answered by Walter Whiteley. 





A set of points in space 
20020318 

From Victoria: Describe the given set with a single equation or a pair of equations: The set of points in space that lie 2 units from the point(0,0,1) and at the same time 2 units from the point (0,0,1). Answered by Penny Nom. 





The "pi" of a circle in hyperbolic space 
20011119 

From Alex: How can you find the "pi" of a circle in hyperbolic space (or is it the same). I would like to know because our environment is hyperbolic and if the "pi" of hyperbolic space is irrational, it would follow that space is non discrete. I would greatly appreciate any help in this question. Answered by Walter Whiteley. 





Arc of a sphere 
20010304 

From Some students: My friends and i have a geometry project and we cannot seem to figure out how to find the arc of a sphere. Answered by Harley Weston. 





Faces 
20010221 

From Sandy: How many faces are there on a sphere? What are the faces of a cone? What is the definition of a "face" of a 3D object? Answered by Walter Whiteley. 





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. 





Volume of a sphere 
20000521 

From Kevin Partridge: Does anyone have a way to physically demonstrate how to explain the volume formula for a sphere? Or perhaps how to derive the formula without calculus? Answered by Harley Weston. 





Reflection off a sphere 
20000512 

From Mark Adami: Given two points P,E and a sphere. Find a point on the sphere, T, so that a line from P that bounces off the sphere at T goes through point E. Answered by Chris Fisher and 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. 





Angles 
20000106 

From Rayna: I am doing a presentation report on angles which has to be fun and entertaining as well as educational. I am having problems locating resources on angles that give me ideas of fun entertaining projects. My lecture is to be about 20 minutes long infront of a class of 11th and 12th graders. Please Help if you can. Answered by Claude Tardif and Walter Whiteley. 





Volume of an ellipsoid 
19991206 

From Michael Nowicki: I am a physician at the University of Mississippi. I am trying to compare the size of polyps (abnormal growth of tissue in the colon) between 2 groups of individuals. The department of pathology gives the size as length X width X depth  how do I calculate the volume? Polyps are nearly ovoid in shape. Answered by Walter Whiteley. 





Some Calculus Problems. 
19971030 

From Roger Hung:
 What real number exceeds its square by the greatest possible amount?
 The sum of two numbers is k. show that the sum of their squares is at least 1/2 k^2.
 .
. . Answered by Penny Nom. 





Three Spheres 
19970114 

From Alan Schnerch: Three spheres of diameter 2 are placed on a level surface so that each sphere touches the other two. A fourth sphere, also of diameter 2, is placed on top of the other three so that it touches all of the other spheres. The distance from the level surface to the highest point of the top sphere is . . .. Answered by Chris Fisher and Harley Weston. 





Volume d'une sphere entre 4 autres spheres 
20100118 

From Bonfils: Bonjour,
Je souhaiterais en fait calculer le rayon de la sphère max qui pourrait s'insérer entre 4 sphères de rayon connu.
Merci par avance pour votre réponse.
Sincères salutations Answered by Chris Fisher. 





Une sphere 
20071203 

From karine: voici ce que je dois trouver ; j'aiune boule disco mesurant 48'' de diametre
je veux savoir combien de petit miroir il y a sur cette boule si les petits miroires
on 1'' carré ? Answered by Claude Tardif. 





5 points équidistants sur la surface d' une sphère 
20050815 

From Jean: J' aimerais placer 5 points équidistants sur la surface d' une sphère.
Si vous aviez une formule simple pour un néophyte, cela m' aiderais beaucoup. Answered by Claude Tardif. 





1 ellipsoïde et une sphère 
20050404 

From Tihon: Dans le cadre de mon mémoire réalisé à l'université de Liège (Belgique), je suis amené à savoir si 1 ellipsoïde et une sphère ont ou n'ont pas d'intersection...Quelqu'un peutil m'aider?? Answered by Claude Tardif. 





Un empilement de spheres 
20020416 

From Sébastien: Lorsque j'etais encore a l'universite je me souviens qu'un prof nous avez dit, sans le demontrer (ce n'est pas bien du tout de sa part) que l'espace minimal qui existe dans un empilement de spheres est de l'ordre de 26% Voici plusieurs jours que je cherche a resoudre ce probleme de geometrie, et je n'arrive meme pas a trouver comment l'aborder. Answered by Claude Tardif. 





Le volume d'une sphère 
20000917 

From Pitmill: merci de me donner la formule pour trouver le volume d'une sphère. Answered by Harley Weston. 

