Identify the form of each equation. 5x + 2y = 3 is in (select)
y-8= 5(x – 4) is in (select)
y = 3x + 8 is in (select)
2x – 3y =-4 is in (select)

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?