Question

What are the coordinates of the center and the measure of the radius for a circle whose equation is (x+9)²+ (y +4)² = 81? O center = (9,4), radius = 81 O center = (9,4), radius = 9 O center = (-9, -4), radius = 9 O center = (-9, -4), radius = 81

Answer 1

centre = (- 9, - 4 ) , radius = 9

Explanation:

the equation of a circle in standard form is

(x - h)² + (y - k)² = r²

(h, k ) are the coordinates of the centre and r is the radius

given

(x + 9)² + (y + 4)² = 81 , that is

(x - (- 9))² + (y - (- 4))² = 9² ← in standard form , then

centre = (- 9, - 4 ) and radius = 9