What is the center and radius of the circle with equation #36x^2 - 36x + 36y^2 - 24y = 131#?

1 Answer
Jan 29, 2016

The General equation of circle is : #x^2 + y^2 + 2gx + 2fy + c = 0#

Explanation:

So,
Dividing all terms by 36 ( To remove the coefficient of x^2 and y^2)
We get,
#x^2 - x + y^2 + 2/3 y = 131/36#
Now
#x^2 - x + y^2 + 2/3 y- 131/36 = 0#

Comparing the given equation with the general equation of circle we get,

2g = #-1#
or g = #-1/2#

Again,
2f = #2/3#
or f = #1/3#

And,

c= #-131/36#

Thus,
Center of the circle (h,k) = (#-g ,-f #)
= (#1/2 , -1/3#)
And
Radius = #sqrt(g^2+f^2-c)#