# CBSE Class 9 Maths Quadrilaterals

#### Types and Angle Sum Property

A quadrilateral is a closed figure of four sides.

Sum of the angles of a quadrilateral is 360 degree.

Different types of quadrilaterals are: Parallelogram with opposite sides parallel and equal in length Square, rhombus and rectangle all are parallelograms with special properties.

Trapezium and kite are other quadrilaterals.#### Parallelograms: Basic Properties

A diagonal of a parallelogram divides it into two congruent triangles.

In parallelogram opposite sides are equal.

A quadrilateral is parallelogram if its opposite sides are equal.#### Angle Relations in Parallelogram

A quadrilateral is a parallelogram if both the pair of opposite sides are parallel to each other.

In a parallelogram both pairs of opposite angles are equal in measure.

A quadrilateral is a parallelogram if both pairs of opposite angles are equal in measure.#### Parallelograms: Diagonal Properties

Diagonals of a parallelogram bisect each other. If the diagonals of a quadrilateral bisect each other then it's a parallelogram.

Diagonals of a rectangle are equal to each other.Diagonals of a square and rhombus are perpendicular bisectors of each other.

If the diagonal of a parallelogram bisect one of its angle then it also bisects the other angle.#### Mid-Point Theorem

The line segment joining the mid points of any two sides of a triangle is parallel to the third side and is half of its length.

A line through the Mid Point of a side of a triangle parallel to another side bisects the third side.

If the intercepts made by a transversal on one side of a pair of parallel lines are equal then they are equal on the other side as well.