Perimeter of the triangle = Sum of all sides =13+13+a=50=>a=24cm
Let the side of length 24cm, be the base of the triangle.
Since the height of the triangle, divides it into two right angled triangles,
132=h2+122
h2=169−144=25
h=√25=5 cm
Now, area of triangle =12×base×height=12×24×5=60 sq cm