One day, Janelle and her parents take a helicopter from the island to a nearby city. What is Janelle's position relative to sea level while in the helicopter? What should the altimeter read at this position?

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?