Question

Line AB is tangent to circle C, AB= 4 inches, and AD = 2 inches. Find the radius of the circle.

Answer 1

Let the radius of the circle be x, then by the tangent-secant theorem
4^2 = 2(x + 2)
16 = 2x + 4
2x = 16 - 4 = 12
x = 12/2 = 6

Therefore, the radius of the circle is 6 inches.