Math Is Fun Forum

Greaterpathmagician

Member

Registered: 2009-06-16

Posts: 32

the formula for finding the radius of the circle

Hello

A regular pentagon inscribed wihin a circle has an area of 1400cm^2
determine
(i) the radius
ii)perimeter of the pentagon

I only know how to find the radius of the cricle with the length of a side is given. Is there are formula for this question

Thank you for any help

Last edited by Greaterpathmagician (2009-10-12 00:45:24)

bobbym

bumpkin

From: Bumpkinland

Registered: 2009-04-12

Posts: 109,606

Re: the formula for finding the radius of the circle

Hi Greaterpathmagician;

You have the area and the number of sides, so you can solve for the radius using this:

Once you have the radius you can use this for the perimeter P.

Last edited by bobbym (2009-10-12 13:35:12)

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