### Quadrilaterals - Revision Notes

CBSE Class 09 Mathematics

Revision Notes

CHAPTER 8

QUADRILATERALS

- Angle Sum Property of a Quadrilaterals
- Types of Quadrilaterals
- Properties of a Parallelogram
- The Mid-point Theorem

- Sum of the all angles of a quadrilateral is
- A diagonals of a parallelogram divides it into two congruent triangles.
- In a parallelogram

- diagonals bisects each other.
- opposite angles are equal.
- opposite sides are equal

(4) Diagonals of a square bisects each other at right angles and are equal, and vice-versa.

(5) A line through the mid-point of a side of a triangle parallel to another side bisects the third side. (Mid point theorem)

(6)The line segment joining the mid-points of two sides of a triangle is parallel to the third side and equal to half the third side.

(7) In a parallelogram, the bisectors of any two consecutive angles intersect at right angle.

(8) If a diagonal of a parallelogram bisect one of the angles of a parallelogram it also bisects the second angle.

(9) The angle bisectors of a parallelogram form a rectangle.

(10) Each of the four angles of a rectangle is right angle.

(11) The diagonals of a rhombus are perpendicular to each other.