Quadrilateral means “four sides”. Therefore, any four sided shape is a quadrilateral, but the sides have to be straight, and it has to be 2 dimensional.
- Square: Four equal sides. Four equal angles, always 90°.
- Rectangle: Opposite sides are parallel and of equal length. Four equal angles, always 90°.
- Rhombus: Four equal sides. Opposite angles are parallel.
- Trapezium/trapezoid: Has one pairof parallel sides.