Question

The sides of a triangle are 5cm, 12cm and 13cm, then its area is:

• A. $24c{m}^2$
• B. $26c{m}^2$
• C. $30c{m}^2$
• D. $35c{m}^2$

Answer 1

The correct option is C

$30c{m}^2$

$s=\frac{5+12+13}{2}=\frac{30}{2}=15cm$

Area of triangle $=\sqrt{s(s-a)(s-b)(s-c)}$

$=\sqrt{15(15-5)(15-12)(15-13)}$

$=\sqrt{15\times 10\times 3\times 2}$

$=\sqrt{3\times 5\times 2\times 5\times 3\times 2}$

$=3\times 5\times 2=30c{m}^2$