







7 spheres on a hexagonal tray 
20190114 

From herm: what is the length of each side of a hexagonal tray, with the height of each side 0.75 inch, to hold seven spheres, each with a diameter of 3.00 inches? The spheres are placed such that each side of the hexagon is touched by one sphere at its midpoint (and the seventh sphere is place in the center of the "ring" of the other six spheres. Answered by Harley Weston. 





A circle problem 
20180330 

From ahamed: the diameters of a circle AB and CD intersect each other at O perpendicularly. Then a chord DF is drawn. AB and DF intersect at E. DE=6cn and EF=2cm.find the area of thw circle Answered by Penny Nom. 





The inside diameter of a silo 
20170228 

From JOHN: I need to find the inside diameter of a cement silo with an outside circumference
118 ft and a wall thickness of 7 inches. thank you John Kerr. Answered by Penny Nom. 





The diameter of the top of a truncated cone 
20160124 

From Peter: I am trying to calculate the diameter of a truncated cone given
one diameter the height of the cone and a 10% taper from one end
to the other. For example a butter churn is 18" tall and 9" in
diameter at the base. the sides need to slope inward at 10%
What is the diameter at 9" and 18" Answered by Penny Nom. 





A diameter of a circle 
20151227 

From sahil: Find the equation of diameter of circle x2 +y26x +2y8 which passes through the origin. 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. 





How does pir^2 = 1/4pid^2? 
20141014 

From al: Hi I cant work out the algebra. How does pir^2 = 1/4pid^2 Thanx Answered by Penny Nom. 





Cutting a hexagon from a disk 
20140405 

From Paul: I am a machinist and sometimes need to make a hex from
round material.
If I know the distance of the flat sides opposite one another
of my hex, how can I calculate the size of material I need to turn
to give me the right diameter to finish the part with six sides? Answered by Penny Nom. 





The diameter of the base of a cone 
20140223 

From elwin: i have a sector of a circle that has 120 degree and 6 cm length. What will be the diameter of the base of the cone.
and what is the diameter of the angle is changed to 180. 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 diameter of a cake 
20110606 

From nurul: Best Bakery shop received an order from your school to bake a 5kg of round cake for teachers day celebration. if a kilogram of cake has a volume of 3800cm^3,and the height of cake is to be 7.0cm, calculate the diameter of the baking tray to be used to fit the 5kg cake ordered by your school?(used pai=3.142) Answered by Penny Nom. 





The perimeter of a semicircle 
20110129 

From Keith: I have the perimeter of a semi circle of 37 but how do I calculate the diameter from this.
This is all the information I have. Answered by Penny Nom. 





The diameter of a cylinder 
20110118 

From Gayle: Given a cylindrical container that holds 45 imp. gallons and is 42 inches high, find the diameter Answered by Penny Nom. 





The diameter of a circle 
20100624 

From John: Piece of wire 72cm in length bent to make semicircle and diameter.Find
length of diameter.Answer given 28cm.How is this arrived at?Looked at
circumference in various ways but failed to understand how 28 cm was
arrived at.Thanks for the help. Answered by Robert Dawson. 





The diameter of a circle 
20100430 

From Jimmy: If I have a straight line with a known length and decide to make a circle out of this know length how would I calculate what the diameter of the circle would be Answered by Penny Nom. 





A truncated cone 
20091111 

From Lucian: I need to calculate the bottom inside diameter of a truncated cone.
The top insdie diameter is 1450mm.
The material is 6mm thick
The cone angle is 20 degrees
The slant length is 152mm
I would like a formula so that I can build a spread sheet Answered by Penny Nom. 





Height of a Flag Pole 
20090626 

From Jake: Can anyone answer this I am very stumped.
The flagpole on the roof of a Chocolate Factory is 13 cm in diameter and
a perfect cylinder. If one end of a 2300cmlong string is attached to the top
of the flagpole, and wraps around the flagpole exactly 16 times before ending
at the bottom of the flagpole, how tall is the flagpole? Need answer by Wednesday Answered by Penny Nom. 





A 27 inch diameter octagon 
20090404 

From Gary: I am trying to build an octagon with 27 in outside diameter, i could make it 28 if it makes the calculations easier. Anyway i need to figure out the length of each individual piece of the octagon. I have tried and i can't get it, please help
Thanks Gary Answered by Harley Weston. 





The diameter of a roll of plastic 
20090324 

From truong: hi. i have trouble to calculate the diameter of the plastic roll. the sheet is 765 m long and 0.8 mm to wrap around the core 400 mm in dia. please help me with the formula to calculate the dia of plastic roll, thanks in advance Answered by Harley Weston. 





A circular plaque in a square box 
20081128 

From kmart: A square box has a diagonal of length 640cm.It is to contain a circular wall plaque. What is the
approximate diameter of the largest wall plaque that can be placed in the box? Answered by Penny Nom. 





The diameter of a circle 
20081101 

From lupito: a circle has a 30`sector,33pi.find the diameter of the circle.How do I set the equation up. Answered by Victoria West. 





A roll of film 
20081016 

From John: I need to know how to calculate the build up on a roll of film is calculated.
Example: I start with a 6" diameter core, and I start winding .005" thick film on the core, so I am adding a total of .010" to the diameter each wrap.
If I continue to do this for a total length of film of 3000 feet, what will the roll diameter be?
So what I need is the formula to perform this type of calculation.
Can you help me? I want to be able to plug the formula in a spread sheet and to be able to input a core diameter, a film thickness and a total length and get a roll diameter. Answered by Penny Nom. 





The sides of an octagon 
20080921 

From mark: I need to know the measurements of an octagon with a inside diameter of 34.5 inches from side to side Answered by Penny Nom. 





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 sides of an octagon 
20080507 

From Frank: Question from Frank, a parent:
Hi,
Need to lay out a 10 ft. diameter octagon on the ground. What is the
length of the
sides ? And the angles ? Answered by Harley Weston. 





The diameter of a circle 
20080428 

From Mary: What is the diameter of a circle if the area is 132.7 square meters? I have tried the formula C=2 times pi radius and came up up 21.1. I also tried C = pi times d and came up with 42.26. The answer in the book says 13. How did they get this answer? Thank you for your help. 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. 





A radius and a tangent to a circle 
20071204 

From elizabeth: show that the radius of a circle meets a tangent line to the circle in a 90 degree angle.
hint: start by assuming they are not perpendicular and at a contradiction. Answered by Penny Nom. 





The diameter of a gasket 
20071201 

From Jorge: I have an application where I am using a circular silicone gasket. I have the total length but would like to calculate the diameter with the given length. What formula should be used? We receive these gaskets in a roll and cut them about 21 inches and glue the ends together to make it one piece. I would prefer to purchase these already cut and glued but require a diameter. If I had the overall diameter from a 21 inch length gasket, I can look online for a part that comes close to the diameter.
Jorge Answered by Harley Weston. 





The diameter of an octagon 
20071012 

From Lewis: How do I calculate the dimension of the diameter of an Octagon when each leg has a dimension of 60 feet? Answered by Penny Nom. 





Diameter of an octagon 
20070807 

From Bree: I am trying to find the diameter of a octagon with 20' sides . What formula do I use? Answered by Stephen La Rocque. 





Area of a circular garden 
20070618 

From Cynthia: Hi is this the correct formula for this problem?
What is the approximate area of a circular garden that is 20 feet in
diameters? Answered by Stephen La Rocque. 





Swimming pool water 
20070412 

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





What is the diameter of the planet? 
20061207 

From Niall: In April 2005, scientists claimed to have captured light from an extrasolar planet orbiting a brown dwarf in the constellation Hydra some 230 lightyears from Earth. The scientists believe the planet is about five times the mass of Jupiter.
Assume the planet has the same density as Jupiter. What is the diameter of the planet? Answered by Stephen La Rocque. 





How do I calculate the roll diameter? 
20061105 

From Bob: if I have the RPM of the roll and the thickness of the web coming off the roll and the mm/min of the web how do I calculate the roll diameter? Answered by Stephen La Rocque. 





Find the radius knowing the chord length and... 
20060728 

From Jim: If I know the length of a chord and its distance from the diameter, how do I calculate the radius of the circle?
Answered by Stephen La Rocque. 





A 9 foot diameter circle 
20060702 

From Lisa: How do I calculate 9 foot diameter measurement in total feet?? Answered by Stephen La Rocque. 





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 diameter of a pipe 
20060127 

From An other:
I know the base length of my arc (10 inches)  I also know the height at the center to the arc (2 inches). I don't think the end is at the midpoint tho. How do I figure out how long the arc length is?
My question involves being able to cut a round pipe into an arc that is 10 inches wide and 2 inches tall. I need to know the smallest diameter pipe to buy in order to fulfill these requirements.
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. 





The diameter of a 800 km circle 
20050122 

From Mechelle: What is the diameter of a 800 km circle? 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. 





Wrap a rope around the equator 
20030212 

From Ali: If you take a rope and wrap it around the equator and then overlap it 6ft. and cut off the extra then you loosen it up so the ends meet how far would it stand off the ground? 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. 





Diameter of a pipe 
20020216 

From Landry: I am trying to calculate the dia. of a pipe 60 inches long that will hold a gallon of water. What is the formula? 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. 





A chord length 
20001017 

From Al Paas: How to determine the length of a chord given the diameter of the circle and the maximum distance from the chord to The circle? 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 
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. 





A Hexagon 
19980922 

From Lee Curtis: Could someone calculate this for me? If a hexagon is 38 feet 8 inches across, how wide would each of the six sides be? Thank you, Lee Curtis Answered by Chris Fisher and Harley Weston. 





Pi 
19971031 

From Ryan McKinnon: What Is Pi? Answered by Chris Fisher. 





The diameter of the sun. 
19961029 

From Lynda Mow: What is the process for solving the following question? As viewed from earth, the sun subtends an angle of approx 32'. If the sun is 93,000,000 miles from earth, find the diameter of the sun. Answered by Penny Nom. 

