Finding supplementary angles

 

Let’s do this by examples

 

Find supplementary angle of 100°

 

Given angle  = 100°

 

We know that,

  If two angles are supplementary, their sum is 180°

 

So,

Angle 1 + Angle 2 = 180°

100° + Angle 2 = 180°

Angle 2 = 180° − 100°

Angle 2 = 80°

 

So, supplementary of 100° is 80°       

 

Find supplementary angle of 90°

Given angle  = 90°

 

We know that,

  If two angles are supplementary, their sum is 180°

 

So,

Angle 1 + Angle 2 = 180°

90° + Angle 2 = 180°

Angle 2 = 180° − 90°

Angle 2 = 90°

 

So, supplementary of 90° is 90°      

 

Find supplementary angle of 55°

Given angle  = 55°

 

We know that,

  If two angles are supplementary, their sum is 180°

 

So,

Angle 1 + Angle 2 = 180°

55° + Angle 2 = 180°

Angle 2 = 180° − 55°

Angle 2 = 125°

 

So, supplementary of 55° is 125°      

 

Find supplementary angle of 125°

Given angle  = 125°

 

We know that,

  If two angles are supplementary, their sum is 180°

 

So,

Angle 1 + Angle 2 = 180°

    125° + Angle 2 = 180°

               Angle 2 = 180° − 125°

       Angle 2 = 55°

 

So, supplementary of 125° is 55°      

 

Among two supplementary angles, the measure of the larger angle is 44° more than the measure of the smaller. Find their measure .

 

Let larger angle be ∠1

and smaller angle be ∠2.  

 

Given,

   ∠1 = ∠2 + 44°

 

We know that,

If two angles are supplementary, their sum is of 180°

 

∴∠1 + ∠2 = 180°  

 (∠2 + 44°) + ∠2 = 180°

 

∠2 + 44° + ∠2 = 180°

∠2 + ∠2 = 180° − 44°

  2 × ∠2 = 136°

 ∠2 = (136°)/2

 ∠2 = 68°

 

Now,

  ∠1 = ∠2 + 44°  

  ∠1 = 68° + 44°

  ∠1 = 112°

So, Required angles are of 112° and 68 °  

  1. Chapter 5 Class 7 Lines and Angles
  2. Concept wise

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Davneet Singh
Davneet Singh is a graduate from Indian Institute of Technology, Kanpur. He has been teaching from the past 8 years. He provides courses for Maths and Science at Teachoo. You can check his NCERT Solutions from Class 6 to 12.