Q1 of 13 Page 199

The base of a prism is an equilateral triangle of perimeter 15 centimetres square and its height is 5 centimetres. Calculate its volume.

Given: base of prism is equilateral triangle and perimeter of base “p” = 15cm2

Height of prism “h” = 5cm


To find : Volume “V” of the prism = ?



Procedure :


As we know that, base of prism is equilateral triangle and its perimeter is 3× side of triangle


⇒ p = 3× side


⇒ 15 = 3× side


∴ side of the triangular base of the prism = = 5cm


Now, area of the equilateral triangular base of the prism,


“a” = × side2


= ×52


= ×25


⇒ a = 10.83cm2


As we know that, Volume of the prism = height × area of base


∴ V = h × a


= 5 × 10.83


= 54.15cm3


∴ Volume of the given prism is 54.15cm3.


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