Question

Find the side of a piece of cloth in the shape of an equilateral triangle, whose area costs as much to paint at Rs 10/ square metre as it would cost to lay a border around the three sides at Rs 25 per metre?

• A. 13.33 m
• B. 17.32 m
• C. 14.14 m
• D. 8.66 m

Answer 1

The correct option is B 17.32 m

Option (b)

Perimeter = 3a

Area = $\frac{\sqrt{3}}{4a^2}$

10x$\frac{\sqrt{3}}{4a^2}$= 25x3a

a=$\frac{30}{\sqrt{3}}$ = 17.32 m