Respuesta :

General equation of a circle:
(y-k)² + (x-h)² = R², where h and k are the center of the circle, which is O(-2,5)

(y-5)² + (x + 2)² = R², but this circle passes through (4,-3). Then:

(-3 - 5)² + (4+2)² = R²

64 + 36 = R²

R² = 100   and R = 10