# CBSE Class 9 Mathematics/Quadrilaterals.

**CBSE Class 9 Mathematics/Quadrilaterals is about the important points about Quadrilaterals. From this you will get an idea about the properties of different type of quadrilaterals.**

**CBSE Class 9 Mathematics/ Quadrilaterals – Chapter 8Important points about Quadrilaterals.Important points to remember:**

**A four sided polygon is called a Quadrilateral.**

*A quadrilateral has 4 sides, 4 angles and 4 vertices.**Sum of the angles of a quadrilateral is 360 degree.****In a parallelogram,**

i) Opposite sides are equal.

ii) Opposite angles are equal.

iii) Diagonals bisect each other.

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

*Diagonals of a rectangle bisect each other and are equal and vice-versa.

*Diagonals of a rhombus bisect each other at right angles and vice-versa.

*Diagonals of a square bisect each other at right angles and are equal, and vice-versa.

*In a square,

i) All sides are equal

ii) All angles are 90 degree.

iii) Diagonals are equal

iv) Diagonals bisect each other at right angles.

*In a Rectangle,

i) Each angle is 90 degree

ii) Diagonals are equal

*In a rhombus,

i) All sides are equal

ii) Diagonals bisect each other at right angle

*In a trapezium,

i) Only one pair of opposite sides is parallel.

ii) Trapezium is not a parallelogram

*In a kite,

i) Two pairs of adjacent sides are equal

ii) Kite is not a parallelogram

*The quadrilateral formed by joining the mid-points of the sides of a quadrilateral, in order, is a parallelogram.

*Square, rectangle and rhombus are all parallelograms.

*A square is a rectangle and also a rhombus.

*A parallelogram is a trapezium.

*The line segment joining the mid-points of two sides of a triangle is parallel to the third side.