Question #N760
A circle has a diameter of 10 units. What is the area of the circle? (Express your answer in terms of $\pi$.)
A. 5$\pi$
B. 10$\pi$
C. 25$\pi$
D. 100$\pi$
Correct Answer is: C
The area of a circle is given by the formula $A = \pi r^2$, where $r$ is the radius of the circle. Since the diameter is 10 units, the radius is 5 units. Substituting 5 for $r$ in the formula yields $A = \pi (5)^2$, or $A = 25\pi$.