# Thread: Equation of a circle

1. ## Equation of a circle

A circles equation is xsquared+ysquared=180
is the point (6,k) is on the circle, determine a value for k.

2. Originally Posted by euclid2
A circles equation is xsquared+ysquared=180
is the point (6,k) is on the circle, determine a value for k.
The statement (6,k) is on the circle $x^2 + y^2 = 180$ means x=6 and y=k satisfies $x^2 + y^2 = 180$

So substitute x=6 and y=k and find out k.

3. Originally Posted by euclid2
A circles equation is xsquared+ysquared=180
is the point (6,k) is on the circle, determine a value for k.
x^2+y^2=180
since (6,k) lie on circle,it will satisfy the equation.so
6^2+k^2=180
k^2=180-36=144
so k=+-12(i.e plus minus 12)