Using the vertical line test, determine if the graph above shows a relation, a function, both a relation and a function, or neither a relation nor a function.
A. neither a relation nor a function
B. both a relation and a function
C. function only
D. relation only

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?