Question

In isosceles $\Delta$ has perimeter 30 cm and each of the equal sides is 12 cm. Find the area of the $\Delta$.

Answer 1

R.E.F image

Perimeter $=30cm$

$12+12+x=30$

$\therefore x=30-24$

$\therefore x=6cm$

Semi-perimeter $=\frac{30}{2}=15cm$

By Heron's formula,

Area $=\sqrt{S(S-a)(S-b)(S-c)}$

$=\sqrt{15(15-12)(15-12)(15-6)}$

$=\sqrt{15\times 3\times 3\times 9}$

$=\sqrt{1215}=34.85c{m}^2$