Math Is Fun Forum

aco

Member

Registered: 2009-10-04

Posts: 2

circle

Write an eqatin for the circle with the given center(2,1) and radius 4

mathsyperson

Moderator

Registered: 2005-06-22

Posts: 4,900

Re: circle

Well, the general equation for a circle is (x-a)² + (y-b)² = r², where a, b and r change depending on the size and position of the circle.
Try playing with those variables until you get the circle you want.

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Why did the vector cross the road?
It wanted to be normal.

bobbym

bumpkin

From: Bumpkinland

Registered: 2009-04-12

Posts: 109,606

Re: circle

Hi all;

The formula mathsy provided usually comes with h and k instead of a and b. It has center (a,b) and radius r.

Substitute:

(x-2)^2+(y-1)^2=16 then go here

http://www.mathsisfun.com/data/grapher-implicit.html

You will see that you have a center of (2,1) and a radius of 4.

Last edited by bobbym (2009-10-04 12:01:40)

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In mathematics, you don't understand things. You just get used to them.
If it ain't broke, fix it until it is.
Always satisfy the Prime Directive of getting the right answer above all else.