Stephen is making a map of his neighborhood. he knows the following info: the distance from his home to the park is 10 blocks the distance from his home to his friends house is 15 blocks the distance from the grocery store to his home is 9 blocks

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?