Question

What is the equation of a circle with a center at (3,7) and a radius of 12?

A: (x-3)2 + (y-7)2 = 144
B: (x+3)2 + (y+7)2 = 144
C: (x+3)2 + (y+7)2 = 12
D: (x-3)2 + (y-7)2 = 12

Answer 1

A

Explanation:

the equation of a circle in standard form is

(x - h)² + (y - k)² = r²

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

here (h, k ) = (3, 7 ) and r = 12 , then

(x - 3)² + (y - 7)² = 12² , that is

(x - 3)² + (y - 7)² = 144 ← equation of circle