Answer:
The area of triangle is 59.2 in².
Explanation:
If a, b and c are three sides of a triangle then the area of triangle by heron's formula is
.... (1)
where,

From the given figure it is clear that the length of sides are 12 in, 18 in and 28.8 in. The value of s is

Substitute s=29.4, a=12, b=18 and c=28.8 in equation (1).




Therefore the area of triangle is 59.2 in².