Let cos(2x) - cos(x) = 0 where 0° < x <180° what are the possible values of x

Name the quadrilaterals that have four equal sides.

Acircular hot tub located near the middle of a rectangular patio has a diameter of 48 inches. the patio measures 11 feet by 6 feet. what is the area of the patio that is not covered by the hot tub?

Find an equation of the line perpendicular to the graph of 28x-7y=9 that passes through the point at (4,1)