Each of the equal sides of an isosceles triangle is 13 cm and its base is 24 cm. The area of the triangle is

(c) $60 \mathrm{~cm}^{2}$

Area of isosceles triangle $=\frac{b}{4} \sqrt{4 a^{2}-b^{2}}$

Here,

$a=13 \mathrm{~cm}$ and $b=24 \mathrm{~cm}$

Thus, we have :

$\frac{24}{4} \times \sqrt{4(13)^{2}-24^{2}}$

$=6 \times \sqrt{676-576}$

$=6 \times \sqrt{100}$

$=6 \times 10$

$=60 \mathrm{~cm}^{2}$