# Quadrilaterals Class 9 Maths Formulas Hey, students are you looking for Quadrilaterals Class 9 Maths Formulas? If yes. Then you are at the right place. In this post, I have listed all the formulas of Quadrilaterals class 9 that you can use to learn and understand the concepts easily.

If you want to improve your class 9 Math, Quadrilaterals concepts, then it is super important for you to learn and understand all the formulas.

With the help of these formulas, you can revise the entire chapter easily.

## Quadrilaterals Class 9 Maths Formulas

Quadrilateral: A plane figure bounded by four line segments is called quadrilateral.

In quadrilateral $\mathrm{ABCD}, \mathrm{AB}, \mathrm{BC}, \mathrm{CD}$ and $\mathrm{DA}$ are sides; $\mathrm{AC}$ and $\mathrm{BD}$ are diagonals and $\angle \mathrm{ABC}+\angle \mathrm{BCD}+\angle \mathrm{CDA}+\angle \mathrm{DAB}=360^{\circ} .$

• Parallelogram: A quadrilateral whose each pair of opposite sides are parallel.
• Rectangle: A parallelogram whose one angle is 90°. Diagonals are equal.
• Rhombus: A parallelogram whose adjacent sides are equal. Note: Diagonal bisect each other at 90°.
• Square: A rectangle whose adjacent sides are equal (four sides are equal). Diagonal bisect each other at 90°.
• Trapezium: A quadrilateral whose one pair of opposite sides are parallel. AB || DC
• Kite: It has two pair of adjacent sides that are equal in length but opposite sides are unequal.

Properties of a Parallelogram
• Opposite sides are equal. e.g., AB = DC and AD = BC
• Consecutive angles are supplementary. e.g., $\angle \mathrm{A}+\angle \mathrm{D}=180^{\circ}$
• Diagonals of parallelogram bisect each other.
• Diagonal divide it into two congruent triangles. A B

• A diagonal of a parallelogram divides it into two congruent triangles.
• In a parallelogram, opposite sides are equal.
• If each pair of opposite sides of a quadrilateral is equal, then it is a parallelogram.
• In a parallelogram, opposite angles are equal.
• If in a quadrilateral, each pair of opposite angles of a quadrilateral is equal then it is a parallelogram.
• The diagonals of a parallelogram bisect each other.
• If the diagonals of quadrilateral bisect each other, then it is a parallelogram.
• A quadrilateral is a parallelogram if a pair of opposite sides is equal and parallel.
• The line segment joining the mid-points of two sides of a triangle is parallel to the third.
• The line drawn through the mid-point of one side of a triangle, parallel to another side bisects the third side.