At a museum, 100 posters are displayed in each of 4 rooms. altogether, how many posters are displayed?

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.

Solve for x: 5/3 x = 20/21 it's fraction. remember to simplify your fraction

Cos^2x+cos^2(120°+x)+cos^2(120°-x)i need this asap. pls me