Question

Write the equation of each circle.

Center at (-1,8) passes through (9,3)

Answer 1

easiest way:
centre is (-1,8) , so the equation is

(x+1)^2 + (y-8)^2 = r^2
sub in the given point (9,3)
r^2 = 10^2 + (-5)^2 = 125

(x+1)^2 + (y-8)^2 = 125

Answer 2

thanks reiny

Answer 3

Write an equation for a circle with center at (–8, 4) and diameter 2.