Question

The cost of laying grass in a triangular field of sides 50m, 65m and 65m at the rate of ₹7 per $m^2$ is ___ .

• A. 10,200
• B. 10,100
• C. 10,500
• D. 10,000

Answer 1

The correct option is C

10,500

Cost of laying grass at the rate of ₹ 7 per $m^2$

$s=\frac{50+65+65}{2}=\frac{180}{2}=90m$

Area of triangular field

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

$=\sqrt{90(90-50)(90-65)(90-65)}$

$=\sqrt{90\times 40\times 25\times 25}$

$=\sqrt{10\times 3\times 3\times 10\times 2\times 2\times 25\times 25}$

$=10\times 3\times 2\times 25=1500m^2$

Cost of laying grass $=7\times 1500$

$=₹.10,500$