In equilateral triangle,

  • All sides are equal
  • All angles all equal 60°

In equilateral ∆ ABC,

  • AB = AC = BC
  • ∠A = ∠B = ∠C = 60°

39.jpg

 

But, why are all angles 60°?

In equilateral triangle, all angles are equal.

Let ∠A = ∠B = ∠C = x

40.jpg

In ∆ABC

Sum of angles is 180°

  ∠A + ∠B + ∠C = 180°

  x + x + x = 180° 

  3x = 180°         

  x = (180°)/3

  x = 60°

 

So, ∠A = ∠B = ∠C = 60 °

Thus, all angles are 60°    

 

For equilateral triangle

42.jpg

Perimeter = 3a

Check proof (link)

Area = √3/4 a^2

Check proof (link)

 

  1. Chapter 6 Class 7 Triangle and its Properties
  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.