**A traffic signal board, indicating ‘SCHOOL AHEAD’, is an equilateral triangle with side ‘a’. Find the area of the signal board, using Heron's formula. If its perimeter is 180 cm, what will be the area of the signal board?**

**Solution:**

Semi-perimeter of triangle

Using** Heron's formula**, area of triangle **where**, s is the semi-perimeter of triangle .

**And,** a, b and c are lengths of sides of triangle.

Area of triangle

**(1)**

If perimeter of equilateral triangle is equal to 180 cm then we can easily find length of each side.

Let length of each side **cm.**

According to the given condition, we have

**cm**

Putting this value in **(1)**, we get

Area of triangle