Am I correct? If not, please explain the right answer, and how you got it

Which graph represents an even function?

98 point question what is the record for most points in one

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?