Question

Find the cost of laying grass in a triangular field of sides $50m,65m$ and $65m$ at the rate of Rs $7$ per $m^2$.

• A. Rs $10500$
• B. Rs $11375$
• C. Rs $10000$
• D. Rs $21000$

Answer 1

The correct option is A Rs $10500$

Sides of the triangle are $a=50m,b=65m,c=65m$
Area of triangle, by Heron's formula $=\sqrt{s(s-a)(s-b)(s-c)}$
where,

$s=\frac{a+b+c}{2}$
$s=\frac{50+65+65}{2}$
$s=90$
Area of triangle = $\sqrt{90\left(40\right)\left(25\right)\left(25\right)}$
Area of triangle = $1500m^2$
Cost of laying grass $=$ Area $\times 7$
Cost of laying grass $=1500\times 7$
Cost of laying grass $=$ Rs $10500$