Find the distance of the two endpoints (-4, -9) and (8, -1).
d = √[(x1 - x2)2 + (y1 - y2)2] = √[(-4 - 8)2 + (-9 - (-1))2]
= √[(-12)2 + (-8)2]√ = √(144 + 64) = √208 = √(16*13) = 4√13 ≈ 14.42 units
The radius of the circle, r, is 7.21 units, which is half of the diameter, d.
Find the center of the circle (midpoint of the diameter).
Xmidpoint: [(-4 + 8)/2] = 4/2 = 2 Ymidpoint: [(-9 + (-1))/2] = -10/2 = -5
h = 2 and k = -5
The equation of the circle is (x - h)2 + (y - k)2 = r2.
(x - 2)2 + (y - (-5))2 = (7.21)2 → (x - 2)2 + (y + 5)2 = 52
