Question

What is the equation of a circle whose center is at the origin and contains the point (7, 0)?

Answer 1

(x-center)^2+(y-center)^2=r^2
x^2+y^2=r^2
(7)^2+(0)^2=r^2
49+0=r^2
r^2=49, r=7
x^2+y^2=49