A square is a quadrilateral with four equal sides and four right angles. The area of a square is side² (also called base × height), or ½ diagonal².

A rhombus is a quadrilateral with four equal sides and four angles that aren't necessarily right angles. The area of a rhombus is ½ diagonal 1 × diagonal 2.

A rectangle is a quadrilateral with two opposite and equal pairs of sides. All angles in a rectangle are right angles. The area of a rectangle is length ×width.

A parallelogram is a quadrilateral with two opposite and equal pairs of sides. The area of a parallelogram is base ×height.

A trapezoid is a quadrilateral with two parallel sides and two nonparallel sides. The area of a trapezoid is ½ (base 1 + base 2) × height.

When making a quadrilateral, the three smallest sides' sum has to be greater than the longest side.

## Rules for quadrilaterals:

squareis a quadrilateral with four equal sides and four right angles. The area of a square is side² (also calledbase×height), or ½diagonal².rhombusis a quadrilateral with four equal sides and four angles that aren't necessarily right angles. The area of a rhombus is ½diagonal1 ×diagonal 2.rectangleis a quadrilateral with two opposite and equal pairs of sides. All angles in a rectangle are right angles. The area of a rectangle islength ×width.base ×height.trapezoidis a quadrilateral with two parallel sides and two nonparallel sides. The area of a trapezoid is ½ (base1 +base2) ×height.