Question

Find the area of a triangle whose sides are $15$ cm, $8$ cm and $17$ cm

• A. $120c{m}^2$
• B. $68c{m}^2$
• C. $136c{m}^2$
• D. $60c{m}^2$

Answer 1

The correct option is D $60c{m}^2$

Area of triangle with sides a, b, and c and s $=\frac{a+b+c}{2}$ is $\sqrt{s(s-a)(s-b)(s-c)}$.

For triangle with sides 15 cm, 8 cm and 17 cm, $s=\frac{15+8+17}{2}=20cm$

Area of the triangle with sides 15 cm, 8 cm and 17 cm $=\sqrt{20(20-15)(20-8)(20-17)}$

$=\sqrt{20\times 5\times 12\times 3}$

$=\sqrt{4\times 5\times 5\times 4\times 3\times 3}$

$=4\times 5\times 3=60{cm}^2$