Question

Find the area of a triangle whose two sides are $4.5cm$ and $10cm$ and perimeter $20.5cm$.

• A. $7.91$
• B. $8.78$
• C. $7.31$
• D. $7.81$

Answer 1

The correct option is A $7.91$

R.E.F image

$P=20.5$

$20.5=4.5+10+x$

$x=6cm$

$S=\frac{Perimeter}{2}=10.25$

Area by Heron's formula -

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

$\Rightarrow \sqrt{10.25(10.25-4.5)(10.25-10)(10.25-6)}$

$\Rightarrow A=7.91c{m}^2$