Question

Which is an equation of a circle with center (-10, 6) and radius 8?

Answer 1

An equation of a circle:

(x - a)² + (y - b)² = r²

(a; b) - a coordinates of a center
r - a radius

r = 8; (-10; 6) ⇒ a = -10 and b = 6

subtitute

(x - (-10))² + (y - 6)² = 8²

Answer: (x + 10)² + (y - 6)² = 64