Question

Find the perimeter of the following shapes:
An equilateral triangle of side $11cm$.

Answer 1

Hint: Since, we know that the perimeter of a plane figure is the sum of its all sides. Hence, the perimeter of an equilateral triangle is calculated by adding its side three times as sides of the equilateral triangle are equal.

Formulas used: Perimeter of a triangle = $sum\,\,of\,\,three\,\,side\,\,or\,\,3 \times \left( {side} \right)$

Complete step by step answer:
 There is an equilateral triangle of side$11\,cm$.

And we know that every triangle has three sides.
Therefore, the perimeter of a triangle is always given as the sum of three sides of a triangle.
Hence, the perimeter of a given equilateral triangle is given as: sum of its all three sides.
$\therefore$ Perimeter of equilateral triangle = $\,\,{S_1}(side\,\,one) + {S_2}\left( {side\,\,2nd} \right) + {S_3}\left( {side\,3rd} \right)$
But, all three sides of an equilateral triangle are of the same length.
$\Rightarrow$ Perimeter of equilateral triangle $= \,\,11 + 11 + + 11 \\$
$\Rightarrow$ Perimeter of equilateral triangle $= \,\,33$

Hence, the perimeter of an equilateral triangle of side $11\,cm$ is $33\,cm.$

Note: We can also find the solution of a given problem in another way. In this we can directly use the fixed mensuration formula of perimeter for an equilateral triangle. Formula of perimeter for equilateral triangle is $3 \times side.$ So, on substituting the value of side in formula, one can directly obtain the perimeter of an equilateral triangle and hence solve the given problem.