Question

What is the area of a triangle whose sides are $3cm$ , $5cm$ and $4cm$?

• A. $6c{m}^2$
• B. $7.5c{m}^2$
• C. $5\sqrt{2}c{m}^2$
• D. none

Answer 1

The correct option is A $6c{m}^2$

Given $a=3cm,b=5cm,c=4cm$

Now $s=\frac{a+b+c}{2}$

Hence $s=\frac{3+5+4}{2}=6$

Now using Heron's Formula

$\Delta =\sqrt{s(s-a)(s-b)(s-c)}$

$\Delta =\sqrt{6(6-3)(6-5)(6-4)}$

$\Delta =6c{m}^2$

$\therefore$ Area of the triangle $=6c{m}^2$