## Saturday, December 15, 2018

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CBSE Class 09 Mathematics
Revision Notes
CHAPTER 8
Angle Sum Property of a Quadrilaterals
Properties of a Parallelogram
The Mid-point Theorem
1. Sum of the all angles of a quadrilateral is
2. A diagonals of a parallelogram divides it into two congruent triangles.
3. 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.