Rules for quadrilaterals:


  • Any four-sided figure is called a quadrilateral.
  • 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.