Question

Find the center and radius of the circle with equation (x + 2)2 + (y + 7)2 = 81.

Answer 1

The equation of a circle is:

(x - h)² + (y - k)² = radius²
where (h, k) is the center of the circle.

Your center is (- 2, - 7).
Your radius is √81 = 9