Question

Choose the equation of a circle with radius 9 and center (3,-4).

Choose the correct answer below.
○ A. (x+3)² + (y− 4)² = 81
○ B. (x − 3)² + (y+4)² = 81
○ C. (x+3)² + (y−4)² = 9
OD. (x-3)²+(y+4)² =

Answer 1

B. (x − 3)² + (y+4)² = 81

Explanation:

If a circle has center located at (a, b) and radius of r, the equation of this circle is

(x - a)² + (y-b)² = r²

We have a = 3, b = -4 and r = 9

So equation is

(x - 3)² + y - (-4))² = 9²

==> (x − 3)² + (y+4)² = 81