Question

the equation (X-2)^2 +(y+4)^2=r^2 represents circle O. The point C(2,0) lies on the circle. What is r, the length of the radius of circle O?

Answer 1

4

Explanation:

(x - 2)^2 + (y + 4)^2 = r^2

You are given a point on the circle, (2, 0).

Plug in 2 for x and 0 for y.

The only variable remaining is r.

Solve for r which is the radius.

(2 - 2)^2 + (0 + 4)^2 = r^2

0^2 + 4^2 = r^2

16 = r^2

r = 4

Answer: The length of the radius is 4.