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
• Adjacent Angles
• Parallel Lines
• Solved Problems on Intersecting Lines
• Solved Problems on Parallel Lines

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