Thread: RADIUS length of circle

The radius length of the circle with equation x^2 + y^2 + 2gx + 2fy + c = 0 is:

A) c
B) -c
C) g^2 + f^2 - c
D) √( g^2 + f^2 - c)
E) g + f

Originally Posted by Joker37

The radius length of the circle with equation x^2 + y^2 + 2gx + 2fy + c = 0 is:

A) c
B) -c
C) g^2 + f^2 - c
D) √( g^2 + f^2 - c)
E) g + f

Completeing squares