Answer:
Step-by-step explanation:
Review the standard equation of a circle with center at (h, k) and radius r:
(x - h)^2 + (y - k)^2 = r^2
A point on (4, -2) has the radius r^2 = (4)^2 + (-2)^2, or r^2 = 20, or r = 2√5. Knowing the center is at (0, 0), we can write:
x^2 + y^2 = 20, or x^2 + y^2 = (2√5)^2
