







A circle in a square 
20200402 

From Sabra: Hello, I have twins in the 7th grade that are learning how to find
circumference of circles. I am struggling with figuring out how to
help my children to find the answer to this question:
Tye has a square piece of yellow felt that has an area of 81
square inches. She wants to cut the largest circle possible from the
material to create a sun for her art project. What is the area of the felt
circle? Use 3.14 for pi. Round to the nearest hundredth if necessary.
I wasn't sure if I am to find the area of the circle through finding the
area of the square or what steps we needed to follow to find the
answer. Once I can see how one is worked out stepbystep, I
usually can help them along with questions that are similar. Answered by Penny Nom. 





The volume of a cylinder 
20200212 

From Mack: I need to find how close the actual volume was of a cylinder (with both ends closed)
to being optimized. Can you please send step by step response?
Height = 11cm
Circumference = 24.4cm
Thanks,
Mack Answered by Penny Nom. 





A thread around a cylinder 
20190428 

From Ally: A cylinder has a diameter of 3.5 cm. How many times will a thread 143mm go round the cylinder? Answered by Penny Nom. 





A circle of circumference 4*pi*r 
20180319 

From Ankith: If the circumference of a circle is 4*pi*r, what is its area?
i) 4*pi*r^2
ii) 2*pi*r^2
iii)3*pi*r^2
iv) pi*r^2 Answered by Penny Nom. 





A rectangle and a circle 
20170812 

From Ramzan: a diagram shows the shape of rectangular framework with length (2x+20)cm and with (y+10)cm . The outline is made of wire . If a circle with diameter 56 cm is to be made from the wire and the area of the rectangle is 420 square centimeter ,find the possible lengths and width of the rectangle Answered by Penny Nom. 





A circle formed from bending a wire 
20161016 

From Deszaree: The same piece of a wire is bent to form a circle
calculate:
a, the radius of the circle
b, the area of the circle Answered by Penny Nom. 





The diameter and circumference of a circle 
20150901 

From Tracey: Hello,
I own a custom workroom, I am figuring out fabric quantities or an estimate. When
at the job site, I forgot to measure the diameter of the semi circle shape that I have to
make a cushion for!!!
If the circumference of the semi circle is 165" what would the diameter be, maybe half
this measurement????
I appreciate any help...I basically need the width from left to right to see if I can fit
the cushion on one width of fabric that is 52" wide! Answered by Penny Nom. 





The area of a circle given the circumference 
20150412 

From F: How do you find the area of a circumference of 6?
Thanks. Answered by Penny Nom. 





The area of a circle in terms of the circumference 
20141104 

From Sarah: How do you find the area of a circle if you already have the circumference?
There was one answer to this question already but it didn't make sense to
me, because they rounded up pi which you can't do so the answer is
incorrect. thanks Answered by Penny Nom. 





The area of a circle of circumference 32.69 meters 
20140611 

From coco: Find the area of a circle with a circumference of 32.69 meters. Answered by Penny Nom. 





A cable around the Earth 
20140313 

From fikile: By how much must an equatorial cable be extended in order that it runs 1meter above the ground? Answered by Penny Nom. 





A reel of cotton thread 
20120605 

From Grace: 91 meters of cotton goes round the cotton reel. About how many times does the cotton go round the reel?
Give your answer to the nearest ten.
(The Diameter of the cylinder is 3cm) Answered by Penny Nom. 





The sarsen circle 
20120421 

From Firdous: I found the circumference but after what to do I am not getting the question is.The diameter of the sarsen circle is 33 meters,since there were originally 30 sarsen stones located on the circumference, how far apart wold the centres of the stones have been?Round to the nearest tenth of a meter. Answered by Penny Nom. 





A fountain 
20120124 

From kris: A fountain has a radius of 14 meters to its outer edge. Their is an inner ring in the center of the fountain, where a statue of Sir Isaac Newton stands, that does not contain water. The inner ring has a diameter that is 6m less than the diameter of the outer ring of the fountain. What is the circumference of the inner ring? What is the area that is covered by water in the fountain? Answered by Penny Nom. 





Two shapes 
20120106 

From muhammad: Question from muhammad, a student:
a boy has two pieces of wire each 99cm long .he bends them into the shapes shown below.calculate the radius of each figure,giving each answer to two decimal places.figures are one is semicircle and other on is half of the semicircle. Answered by Harley Weston. 





The circumference and area of a circle 
20111213 

From Mable: A circle that going 70mi across using 22/7 I need the area,radius, and the circumference
and how to set up the steps can you help? Answered by Penny Nom. 





The perimeter of a quarter circle 
20101215 

From kim: how do you figure the perimeter of a quarter circle that has a radius of 7 inches? I would like to have the explanation of how you figure it out. Thank you Answered by Penny Nom. 





A circular 20 acre lake 
20100813 

From Ken: I jog around a circular 20 acre lake. Please help me learn the distance of the perimeter of the lake so I will know my jogging distance. Thanks Answered by Stephen La Rocque and Tyler Wood. 





The circumference of a circle 
20100512 

From Morgan: find the circumference of a circle with radius 8.
im having trouble i just don't understand. thanks for your help i really do appricate it. Answered by Penny Nom. 





Bending a wire to form shapes 
20100204 

From Geraldine: a wire bent into the shape of a square encloses an area of 25cm squared. then the same wire is cut and bent into two identical circles. what is the radius of one of the circles round to the nearest hundred Answered by Penny Nom. 





A minute hand 
20091105 

From Pardha: A minute hand of table clock is 3cms long. How far its tip move in 20 minutes Answered by Penny Nom. 





A rolling wheel 
20090329 

From Jules: How far does a wheel of radius 2 feet roll along level ground in making
300 revolutions? Answered by Penny Nom. 





The radius of a circle 
20090322 

From Justin: Find the radius of a circle with a circumference of 9.43cm. Answered by Penny Nom. 





The circumference of a table 
20090114 

From Maggie: My dinning room table is 48 inches. I need to know what its Circumference is?
I do not know algebra so a formula will not help me. Answered by Penny Nom. 





How far does the ball travel? 
20081101 

From Betty: This is a question that is perplexing me. I tried to solve it with the Pythagorean Theorem but have not been able to get the right answer. A ball attached to the moving end of the 5meter arm of a pendulum. The pendulum swings through a 90 degree arc once. Approximately how far, in meters, does the ball travel? Answered by Victoria West. 





The area of a square 
20081020 

From Danny: Is it possible to use a circumference measurement to find the area of a square when all 4 corners have a 1.75" radius? Answered by Harley Weston. 





A string around the world 
20080818 

From Terry: I heard this on T.V. and was wondering if it was true. Place a string around
the world, you would need 25,000 miles of string. If you raised the string
off of the ground by 1 foot all the way around. How much more string
would you need? Answered by Penny Nom. 





A circle inscribed in a triangle 
20080426 

From Amar: I have been given a circle inscribed in a triangle and have been told to prove that the ratio of the perimeter of the triangle to the circumference of the circle is the same as the ratio of the area of the triangle to the area of the circle. How would this be done? Answered by Stephen La Rocque and Walter Whiteley. 





The radius of a circle 
20080322 

From danny: waht is the radius of a circle, if the circumference is 800? Answered by Penny Nom. 





The diameter of a circle 
20080303 

From Kathie: I know the length of the curved portion of a semicircle is 200 ft. but I need to find the diameter to get a total perimeter and area. How do I find the diameter to get the perimeter? Answered by Penny Nom. 





The circumference and radius of a circle 
20080210 

From Ray: How do you find the circumference or radius of an area presuming it is a circle. Or in other words how do you find the c or r given only the area is 50 sq metres Answered by Penny Nom. 





The perimeter of circle 
20071215 

From shaquilla: what is the perimeter of a circle. Answered by Penny Nom. 





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. 





A sheet of corrugated iron 
20071003 

From Ashutosh: A sheet of corrugated iron has corrugations based on the arc of a circle of radius of 3 cm and a central angle of 180 degrees. How many corrugations are formed when a flat sheet of steel 1 metre wide is bent to form a sheet of corrugated iron? Answered by Stephen La Rocque. 





A piece of wire is bent in the form of a circle 
20070924 

From Renece: a piece of wire is bent in the form of a circle and it encloses an area of 154cm
a) calculate the radius of the circle
b) the circumference of the circle
use 22/7
The same piece of wire is then bent into a square
d) calculate the area enclosed by the square. Answered by Penny Nom. 





The circumference of a circle 
20070911 

From annette: circumference of a 3.75 ft circle I have not done this in years and forgot how. Answered by Stephen la Rocque and Victoria West. 





Speed of sunrise 
20070904 

From Robert: Facing west in a car, you are watching the sun rise (through the rear view mirror). It peaks the horizon, you take off driving. How fast would you have to drive, to see it rise again? Answered by Stephen La Rocque. 





A round reservoir 
20070814 

From lee: if you have a 46 acre round reservoir, how far around in feet would that be ?? Answered by Penny Nom. 





Finding the area of a circle from its circumference 
20070716 

From Amanda: what is the area of a circle with a circumference of 3000 metres? Answered by Stephen La Rocque. 





Length of a circle 
20070711 

From Debra: i have a radius of 73 inches, i need to know the length of the circle please. Answered by Stephen La Rocque. 





Can't find circumference of an ellipse 
20070706 

From Michele: I need to figure the circumference of an oval and I know the height and width. Answered by Penny Nom. 





Edging around a pool 
20070626 

From Celeste: I have a 27ft. above ground pool. I want to put edging around it but do not know how many feet of edging I need. Can You help? The edging will be approximately 2 feet away from the pool. Answered by Penny Nom. 





What is the size of the circle it would make? 
20070613 

From ed: i have a piece of sheet metal 56' 6" long what is the size of the circle it would make Answered by Penny Nom. 





The circumference of an ellipse 
20070525 

From Graham: I have an ellipse that I need to find the circumference of. It is 40ft at its longest point and 25ft at its shortest Answered by Penny Nom. 





The circumference of part of a circle 
20070506 

From Wallis: I have more then a quater of a circle, but less than half. What is the circumference if the two side are 7cm and the angle between them is 110 degrees? Answered by Penny Nom. 





Swimming pool water 
20070412 

From tina: How much water does a 24' round, 4' deep swimming pool hold? Answered by Haley Ess. 





The length of the diameter 
20060518 

From Steven: A circle has a circumference of 312in. Find the length of its diameter to the nearest integer? Answered by Penny Nom. 





The circumference of a larger circle is twice the circumference of a smaller circle. 
20060120 

From Amanda: The circumference of a larger circle is twice the circumference of a smaller circle. What is the ratio of the radius of the smaller circle to the diameter of the larger circle? Answered by Penny Nom. 





A goat is tied to the corner of a 50 ft square outbuilding 
20051224 

From Danielle: Topic: A goat is tied to the corner of a 50 ft square outbuilding with a 40 ft. rope.
a) What is the measure of the partial circumference created as the goat walks at the full length of the rope?
b) Since the goat is trimming the grass from part of the outbuilding, how much of the perimeter of the outbuilding will the building owner have to trim? Answered by Penny Nom. 





The circumference of an oval pool 
20050518 

From John: I have an oval pool of which I am trying to find the circumference. it is 38 feet long and 19 feet wide Answered by Penny Nom. 





The diameter of a 800 km circle 
20050122 

From Mechelle: What is the diameter of a 800 km circle? Answered by Penny Nom. 





The radius of a circle 
20040306 

From A student: what is the radius of a circle with the circumference of 12 inches? Answered by Penny Nom. 





Circumference 
20030509 

From A parent: Find the circumference use 3 1/7 for pi
1. r= 28 ft. 2. D=98 cm Answered by Penny Nom. 





What really is pi? 
20020905 

From Rachel: what really is pi? 3.1444 Answered by Penny Nom. 





The circumference of a 72 
20020814 

From Linda: What is the circumference of a 72" diameter circle? Answered by Penny Nom. 





The perimeter of an ellipse 
20020214 

From Harry: I am planning to build a coffe table with an ellipse of 24x36 for the top. I wish to decorate the edge and need to know the lenght of the perimeter for lay out purposes. Is there an easy way to approximate this figure with out using intergal calculus? Answered by Penny Nom. 





The distance across a circle 
20020118 

From Douglas: If you know how far around a circle is (say earth) 25000 miles how do you calculate the distance across? Answered by Penny Nom. 





The diameter of an oval 
20010523 

From Tim: Is there a such thing as a diameter of a oval? If not, is there a way to get the circumference? Answered by Claude Tardif and Penny Nom. 





Kai's bike 
20001207 

From Fumiko Muhammad: The wheels on Kai's bike are 27 inches in diameter. His little sister, Masako, has a bike with wheels that are 20 inches in diameter. a. How far will Kai go in one complete turn of his wheels? b. How far will Masacko go in one complete turn of her wheels? c. How far will Kai go in 500 turns of his wheels? d. How far will Masako go in 500 turns of her wheels? Answered by Penny Nom. 





The circumference of a circle 
20000730 

From Not a student: An equalateral triangle is enclosed in a circle. The three corners touch the edges of the circle. One side of the triangle is 12. What is the circumference of the circle? Answered by Penny Nom. 





Circumference = Area 
20000419 

From Scot George: The area and circumference of a circle has the same measurement. Find the radius. Answered by Chris Fisher. 





Perimeter of an ellipse 
20000221 

From Kurtis Proffit: What is the formula for the perimeter or circumference of an ellipse? Answered by Chris Fisher. 





The circumference of a circle 
19991005 

From Mara Frost: what is the formula to find the circumference of a circle, or if there is no formula, how do you find the circumference of a circle? Answered by Penny Nom. 





Circles, cirmcuference and area 
19990516 

From Stephen Ehrler: I would appreciate if you could please tell me if what I discovered here is something or my ignorance? I noticed that a circle with r radii has the folling characteristic. r = [2 * ( pi * r^{2} / pi * 2r)] The equation states that the ratio of a circles area over its circumfrence = 1/2 that of the circles radii. It works every time. Did you know this ? Is it some kind of therom and can it be used for any thing? I thought this was intresting and would appreciate any input you may have. Thank you. Answered by Chris Fisher. 





Circles 
19990421 

From Alex Elkins: How do you find the circumference of a circle if you only know the radius and the square feet or inches of the circle if the radius is 18 inches, If done in inches do you multiply by 12 to get the square feet? Answered by Jack Lesage and Harley Weston. 





Circumference and Area 
19990216 

From Natalie: finding the circumference of a circle? formula finding the area of a parallelogram? formula
Answered by Penny Nom. 





The area and the circumference of a circle. 
19980827 

From Jason Wright: I was looking at the relationship of the area of a circle and the circumference when I realized that 2*pi*r is the derivative of pi*r^2. I was wondering if there is any connective deep dark meaning as to why this appears to be related. Thanks for any help you can give me! Answered by Walter Whiteley. 

