PLEASE HELP AND DO NOT SEND A LINK IF YOU DO YOU WILL BE REPORTED I need help with these problems I'm hella confused about them, I'm not sure if what I put was correct please help me and show explanations

What term best describes a line ans a point that lie in the same plane

Find the distance between (7,-6) and (-3,-9)

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?