If a circle has a diameter of 16 feet, which expression gives its area in square feet?
A. 8^2•r
B. 16^2 •r
C.8•r
D. 16•r

Need on this geometry question. explain how you did it.

Which of the following best describes the delian problem?

You are standing next to a really big circular lake. you want to measure the diameter of the lake, but you don't want to have to swim across with a measuring tape! you decide to walk around the perimeter of the lake and measure its circumference, and find that it's 400\pi\text{ m}400? m. what is the diameter dd of the lake?