# Supplementary Angles

Supplementary angles : When two angles add up to 1800

Example :

1) 60,120 2) 179, 1 3) 90,90 etc.

Important Points

i) Two acute angles can not be supplement of each other.

ii) Two right angles are always supplementary.

iii) Two obtuse angles can not be supplementary of each other.

Examples :

1) The two angles are supplementary. If one of the angle is thrice that of the other then find the two angles.

Solution :
As we know that sum of two supplementary-angles is 180
0

Let one angle be x so other angle be 3x.

x + 3x = 180
0

4x = 180

x = 180/4

x = 45

&ther4; one angle = 45
0

and other angle = 3x = 3 x 45 = 135
0

2) Two supplementary-angles differ by 34
0 . Find the angles.

Solution :
Let one angle = x
0

Other angle = (x + 34)
0

As we know that sum of two supplementary-angles is 180
0

∴ x + x + 34 = 180

⇒ 2x + 34 = 180

⇒ 2x = 180 – 34

⇒ 2x = 146

⇒ x = 146/2

⇒ x = 73

Other angle = 73 + 34 = 107
0

Hence, the measures of two angles are 73
0 and 107 0

Practice

Q.1 Check whether the following angles are supplementary or not.
1) 45
0 and 130 0
2) 30
0 and 115 0
3) 112.8
0 and 67.2 0
4) 1
0 and 179 0
5) 34
0 and 150 0
Basic Geometry

Point
Lines
Angles
Lines and Angles
Complementary angles
Supplementary angles
Vertically Opposite Angles
Linear Pair Angles