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1 Full revolution = 360 ° 

                                     Degree

 

We measure angles in term of degrees.

  1 revolution = 360 °

  1/2 revolution = (360°)/2 = 180°

 

  1/4 revolution = (360°)/4 = 90°

So,

  Right angle =  1/4 revolution = 90°

  Straight angle = 1/2 revolution = 180°

 

Acute Angle

Acute angle is less that right angle.

∴        Acute angle < Right Angle.

          Acute angle < 90°

 

Obtuse Angle

Obtuse angle is greater than right angle, but smaller than straight angle.

Right angle < Obtuse angle < Straight angle.

90° < Obtuse angle < 180°

 

Reflex Angle

Reflex angle is an angel greater than straight angle.

  Reflex angle > Straight angle

  Reflex angle > 180°

 

To summarize,

  Right angle = 90°

   Straight = 180°

  Acute angle < 90°

  Obtuse angle > 90° & Obtuse angle < 180°

  Reflex angle > 180°

  1. Chapter 5 Class 6 Understanding Elementary Shapes
  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.