A quadrilateral is a four sided polygon. The sum of interior angles for all quadrilaterals must be equal to 360 degrees. There are five main types of quadrilaterals each having its own features.

### Square

- All sides are equal in length.
- All angles are right angles.
- Opposite sides are parallel.
- Perimeter = 4 × (side) = 4 × L
- Area = (Side) × (Side) = L × L

### Rectangle

- Opposite sides are equal in length.
- Opposite sides are parallel.
- All angles are right angles.
- Perimeter = 2 × (Length + Breadth) = 2 × (L + B)
- Area = (Length) × (Breadth) = L × B

### Parallelogram

- Opposite sides are equal in length and parallel.
- Opposite angles are equal.
- Adjacent angles are supplementary.
- The diagonals bisect each other.
- Perimeter = 2 × (Length + Breadth) = 2 × (L + B)
- Area = (Length) × (Height) = L × h

### Rhombus

- All sides are equal in length (all angles are not equal).
- Adjacent angles are supplementary.
- Opposite angles are equal.
- Diagonals bisect each other at right angles.
- Perimeter = 4 × (Side) = 4 × L
- Area = (multiple of diagonals)/2

### Trapezoid

- Only one pair of sides is parallel.
- Perimeter = Sum of sides = A + B + C + D
- Area = (Height) × (Sum of parallel sides)/2 = (h) × (A + B)/2