Page 151 - Math Smart - 7

@ ABC is an isosceles triangle and ZBAC = 134^ Q PQR is an equilateral triangle and /-PTS = 46'

Find zlACB. Find APST.

6.5.2 Finding unknown angles in

quadrilaterals

We have learnt some properties of the sides and angles of quadrilaterals earlier.
To solve geometrical problems, we need to make use of these properties of
quadrilaterals.

Quadrilateral Sides Diagonals and height
1. Rectangle Two pairs of Diagonals AC and BD
parallel sides. are equal and bisect
ABII DC, AD II BC each other.
Opposite sides are
equal.
AB = DC, AD = BC

2. Square Two pairs of Diagonals AC and
parallel sides. BD are equal and
ABIIDC,ADIIBC perpendicular. They
also bisect each other.
All sides are equal.
AB = BC=CD = AD

3. Parallelogram Two pairs of Diagonals AC and BD
parallel sides. bisect each other.
ABIIDQADIIBC
Height EF\s
Opposite sides are perpendicular to AD
equal. and BC.
AB = DC, AD = BC