Chapter 1 :

Chapter 1 : POLYGONS I & II

1.1 The sum of the angles of triangle is 180

o

.

a

b

c

0

0

0

0

180

=

+

+

c

b

a

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1.2In the equilateral triangle, all the interior angles are of the same size, that is 60

.

0

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1.3 In isosceles triangle, two angles that are opposite to the two sides with equal length are the same size.

0

0

b

a

=

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1.4Exterior angle of a triangle vertex is equal to sum of opposite interior angles

0

0

0

b

a

x

+

=

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1.5The sum of the angles of a quadrilateral is 360

0

0

0

0

0

0

360

=

+

+

+

d

c

b

a

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1.6Opposite angles in the parallelogram are equal in size

C

A

=

EMBED Equation.3

D

B

=

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1.7Sum of interior angles of a polygon with n sides = (n-2) x 180

0

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1.8The sum of exterior angles of a polygon is 360

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B

A

C

D

60

60

60

a

b

b

a

x

a

b

c

d

Polygons18

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