Question

A triangular wall having sides 3m, 5m and 6m has to be painted. If the cost of painting 1$m^2$ of wall is Rs 5. What is the cost of painting the whole wall?

• A. 16√3
• B. 10√14
• C. 14√10
• D. 12√14

Answer 1

The correct option is B

10√14

Using the Heron's formula, Area (A)= $\sqrt{s(s-a)(s-b)(s-c)}$.

Semi-Perimeter (s) = $\frac{a+b+c}{2}$

s = 7

Area = $\sqrt{7\ast 4\ast 2\ast 1}$ = 2$\sqrt{14}$

Hence the cost = 5A
Cost of the painting = Rs. 10$\sqrt{14}$