Help pls I’ll give extra points

Find the measure of the interior angles of the following regular polygons: a triangle, a quadrilateral, a pentagon, an octagon, a decagon, a 30-gon, a 50-gon, and a 100-gon.

Express the following as a function of a single angle. cos(60) cos(-20) - sin(60) sin(-20)

Combine like terms to make a simpler expression 3z+z