Almost any quadrangle can contain at least one right angle, including trapezoids, kites, rectangles and squares. Rectangles and squares contain four right angles. The opposite sides of rectangles are parallel and of equal length. The opposite sides of squares are also parallel, and each side is the same length.
Squares and rectangles are subsets of parallelograms and rhombuses. However, if a parallelogram or rhombus contains a right angle, it is defined as a rectangle or square, depending on the side lengths.
It is also possible for trapezoids to contain two right angles. Trapezoids are quadrilaterals that have one pair of sides that are parallel, with the other sides not parallel. The angles of trapezoids can vary greatly.