Anyone know how to do this??

The graph below represents the number of dolphins in a dolphin sanctuary. select all the key features of this function.

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?

Which equation can be solved to find x the measure of jk in the apex