Question #N389
In the $xy$-plane, a circle with center $(2,-3)$ is tangent to the line $y = 5$. What is the radius of the circle?
A. 2
B. 3
C. 5
D. 8
Correct Answer is: B
The radius of the circle is the perpendicular distance from the center of the circle to the tangent line. Since the center of the circle is $(2,-3)$ and the tangent line is $y=5$, the radius is the difference between the y-coordinate of the center and the y-coordinate of the line, which is $5 - (-3) = 8$. Therefore, the radius of the circle is 8.