#### Answer

84 $in^{2}$

#### Work Step by Step

Given sides of a triangle
13 in, 14 in, 15 in
Using Heron's formula if three sides of a triangle have length a,b,c then area A of a triangle is
A = $\sqrt s(s-a)(s-b)(s-c)$
where s = $\frac{a+b+c}{2}$
Lets take a=13 b=14 and c=15
s = $\frac{13+14+15}{2}$
= 21 in
A = $\sqrt 21(21-13)(21-14)(21-15)$
=$\sqrt 21*8*7*6$
=84 $in^{2}$