Question

the sides of a triangle are 3cm,4cm,5cm the area is

Answer 1

$a = 3 \: \\ b = 4 \\c = 5 \\ \\ s = \frac{a + b + c}{2} \\ = \frac{3 + 4 + 5}{2} \\ = \frac{12}{2} = 6 \\ \\ by \: herons \: formula \: \\ area \: of \: triangle = \\ \sqrt{s(s -a )( s- b)(s - c)} \\ = \sqrt{6(6 - 3)(6 - 4)(6 - 5)} \\ = \sqrt{6 \times 3 \times 2 \times 1} \\ = \sqrt{6 \times 6} \\ = 6 {cm}^{2}$