Question

What equation represents a circle with a center at (-4,9) and a diameter or 10 units

Answer 1

(x + 4)² + (y - 9)² = 25

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) = (- 4, 9) and r = 10 ÷ 2 = 5 , thus

(x - (- 4))² + (y - 9)² = 5² , that is

(x + 4)² + (y - 9)² = 25 ← equation of circle