ELI5: Explain Like I'm 5

Masreliez's theorem

Maserliez's Theorem is a way to find the area of a shape. It says that if you draw any shape with straight sides, all the angles in the corner have to add up to 360 degrees. That means if you add all the angles together, they should equal 360 degrees. To find out the area, you could multiply the length of one side times the length of another side. That would tell you how many square units the shape has.