Question #N189
A square with side length 8 is inscribed in a circle. What is the area of the circle?
A. 16\pi
B. 32\pi
C. 64\pi
D. 128\pi
Correct Answer is: C
The diagonal of the square is a diameter of the circle. The diagonal of the square has length $8\sqrt{2}$ (using the Pythagorean Theorem or the special 45-45-90 triangle ratio). So the radius of the circle is $4\sqrt{2}$, and the area is $\pi(4\sqrt{2})^2 = 32\pi$.