Question

A traffic signal board ,indicating school ahead, is an equilateral triangle with side'a' .find the ara of signal board , using heron's formula . If its perimeter is 180cm, what will be the area of the signal board?

Answer 1

perimeter of triangle: a+b+c
all sides are same 
therefore,
3a=180
a=180/3=60cm
area 
s=(a+b+c)/2
s=180/2=90
area=sqrt{s*(s-a)*(s-b)*(s-c)}
=sqrt {90*(90-60)*(90-60)*(90-60)}
=sqrt{90*30*30*30}
=sqrt{27000*90}
=sqrt{24,30,000}
=1558.8
~1559 cm sqaure