The triangular side walls of a flyover have been used for advertisements. The sides of the walls are 122 m, 22 m and 120 m (see Fig. 12.9). The advertisements yield an earning of ₹5000 per m2per year. A company hired one of its walls for 3 months. How much rent did it pay?
Solution
The sides of the triangle are 122 m, 22 m and 120 m.
Perimeter of the triangle is 122 + 22 + 120 = 264m
Semi perimeter of triangle (s) = 264/2 = 132 m
Using heron's formula,
Area of the advertisement = √s (s-a) (s-b) (s-c)
= √132(132 - 122) (132 - 22) (132 - 120) m2
= √132 × 10 × 110 × 12 m2
= 1320 m2
Rent of advertising per year = ₹ 5000 per m2
Rent of one wall for 3 months = ₹ (1320 × 5000 × 3)/12 = ₹ 1650000
