Question

One side of an equilateral triangle measures 8cm. Find its area using Heron’s formula. What is its altitude?

Answer 1

Hope this'll help you

Answer 2

as it is said that it is equi. triangle and  of its side is 8 then 
==8+8+8=24, perimeter 
==24/2=12, semi perimeter or S

so, by the Heron,s formula we get √s(s-a)(s-b)(s-c)
 so our a=b=c==8 first we will subtract
12-8=4                 √12×4×4×4
==2×2×2×2√3
==16×1.73=27.68
by the formula 1/2*B*Al.
 we, get 1/2×8×h=27.68
==h=27.68/4=6.92
Here is your ans. 
Height = 6.92