Question

Determine the equation of the circle graphed below. Circle Standard Form: Center: (h, k). Radius: r. (x-h) ^2+(y-k) ^2=r^2. Center: (-7, -4). Radius: -4.

Answer 1

The circle with center (h,k) = (−7,−4) and radius r = |−4| = 4 has equation

(x − (−7))^2 + (y − (−4))^2 = 4^2,

or

(x + 7)^2 + (y + 4)^2 = 16.

(Note: radius is nonnegative, so r = 4; r^2 = 16.)