Question

The edges of a triangular board are 6 cm, 8 cm and 10 cm. Find the cost of painting of one face of triangle at the rate of 9 paise per cm${}^2.$

Answer 1

Given: a = 6 cm, b= 8 cm, c = 10 cm.

$s=\frac{(6+8+10)}{2}=12$

Hence, by using Heron’s formula, we can write:

$A=\sqrt{12(12-6)(12-8)(12-10)}=\sqrt{12\times 6\times 4\times 2}=\sqrt{576}=24c{m}^2$

Therefore, the cost of painting at a rate of 9 paise per cm ${}^2$$=24\times 9$ paise = Rs. 2.16