# 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 1800

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

x + 3x = 1800

4x = 180

x = 180/4

x = 45

&ther4; one angle = 45 0

and other angle = 3x = 3 x 45 = 1350

2) Two supplementary-angles differ by 340. Find the angles.

Solution :
Let one angle = x0

Other angle = (x + 34)0

As we know that sum of two supplementary-angles is 1800

∴ x + x + 34 = 180

⇒ 2x + 34 = 180

⇒ 2x = 180 – 34

⇒ 2x = 146

⇒ x = 146/2

⇒ x = 73

Other angle = 73 + 34 = 1070

Hence, the measures of two angles are 730 and 1070

Practice

Q.1 Check whether the following angles are supplementary or not.
1) 450 and 1300
2) 300 and 1150
3) 112.80 and 67.20
4) 10 and 1790
5) 340 and 1500
Basic Geometry

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