Circle equation

Question

Write the equation of the circle centered at (9,0) that passes through (-13,4).

Answer 1

the general equation for a circle is

(x-h)^2 + (y-k)^2 = r^2 where (h,k) = the center and r = the radius

h=9, k = 0

(x-9)^2 + y^2 = r^2

plug in the point (-13,4) to solve for r^2

(-13-9)^2 + (4)^2 = r^2

22^2 + 16 = r^2

r^2 = 484 + 16 = 500

the equation of the circle is

(x-9)^2 +y^2 =500