RS Aggarwal & V Aggarwal - Mathematics

Book: RS Aggarwal & V Aggarwal - Mathematics

Chapter: 7. Areas

Subject: Mathematics - Class 9th

Q. No. 12 of Exercise 7A

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12

If the area of the equilateral triangle is cm2, find its perimeter.

Given,


Area of the equilateral triangle = 36cm2


Let us assume a be the length of the side of an equilateral triangle


We know that,


Area of an equilateral triangle = sq units


36 =


a2 =


a2 = 36 × 4


a2 = 144


a = 12 cm


We know that,


Perimeter of an equilateral triangle = 3 × a


= 3 × 12


= 36 cm


Hence, perimeter of the given equilateral triangle is 36 cm.


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