What is question 5 pls help

1. what is the phythaforean theorem? 2.what do we use it for? 1.what is the distance formula ? 2.what do we use it for?

What dimensions can créate more than one triangle ?

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?