The area of a triangle is found by multiplying the base by the height. Problem is, that in this example with 3 different sides, you can't easily find out the height.
To the rescue comes Heron's formula:
[tex]s = \frac{a+b+c}{2}
[/tex]
and
[tex]A = \sqrt{s(s-a)(s-b)(s-c)}[/tex]
So s = (25+26+21)/2 = 36
and Area = √36·11·10·15 ≈ 243.7
