Equations of Circles
A circle whose center is (h, k) and whose radius is r is written as:
(x-h)² + (y-k)² = r²
Ex 3: For each equation below, state the circle's center and its radius.
a. (x - 5)² + (y-2)² = 25
Center:
Radius:
h (x + 4)² + v² = 15
c. (x + 2)² + (y + 5)² = 81
Center:
d x² + v² = 9
Radius:
4 of 6