Iwill give 20 points and brainliest for one question if someone gives an explanation and the pls me, and hurry: (

Could somebody me with this radical simplification?

Write two point-slope equations for the line passing through the points (6, 5) and (3, 1)

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?