Question

Perimeter of equlieteral triangle is 21 cm of the area of unshaded part ia36.88cm then the area of unshaded triangle is

Answer 1

First of all it should have to noted that area is always measured in unit² not in simple unit.

So, the correct question is_

Perimeter of equilateral triangle is 21 cm of the area of unshaded part is 36.88 cm² then the area of unshaded part of the triangle is ?

Let, do the sum now_

It is stated that the perimeter of the triangle is 21 cm.

We know that, the perimeter of an equilateral triangle is (3* length of the side).

Hence, the length of the side = (21/3)

                                                 = 7 cm.

We know that, the area of an equilateral triangle is

=$\frac{\sqrt{3} }{4} a^{2}$

Hence, the are of the triangle_

$\frac{\sqrt{3} }{4} 7^{2}$

= $\frac{49}{4} \sqrt{3}$

= (49*1.732)/4              [√3 = 1.738]

= 84.868/4

= 21.22 cm²

So, the area of the unshaded part except the triangle is = (36.88-21.22)

                                                                                            = 15.66 cm²