Question

How to find the area of isosceles triangle ?

Answer 1

Let triangle ABC be an isosceles triangle with AB = AC and BC be the base.
Area of triangle using Heron's formula = sq.rt {s(s-a)(s-b)(s-c)}
where s = semi-perimeter, and a, b and c are the lengths of sides.
In our triangle AB = AC = a cm (say) and BC = b cm (say)
$\to s=\frac{2a+b}{2}=a+\frac{b}{2}$
$\to Area=sq.rt\{a+\frac{b}{2}(s-a\left)\right(s-a\left)\right(s-b\left)\right\}$ sq. units or sq cms if a, b, and c are in cms.