Question

If the area of an equilateral triangle is $81\sqrt{3}c{m}^{2,}$ find its perimeter.

Answer 1

Area of an equilateral $△=81\sqrt{3}c{m}^2$

$\therefore \frac{\sqrt{3}}{4}{a}^2=81\sqrt{3}$

$a^2=81\times 4$

$a=18$

Perimeter of an equilateral $△=3a=3\times 18=54cm$