A floral design on a floor is made up of 16 tiles which are triangular, the sides of the triangle being 9 cm, 28 cm and 35 cm (see Fig. 12.18). Find the cost of polishing the tiles at the rate of 50p per cm2 .
Solution
Semi perimeter of the each triangular shape = (28 + 9 + 35)/2 cm = 36 cm
Using heron's formula,
Area of the each triangular shape = √s (s-a) (s-b) (s-c)
= √36(36 - 28) (36 - 9) (36 - 35) cm2
= √36 × 8 × 27 × 1 cm2
= 36√6 cm2 = 88.2 cm2
Total area of 16 tiles = 16 × 88.2 cm2 = 1411.2 cm2Cost of polishing tiles = 50p per cm2
Total cost of polishing the tiles = Rs. (1411.2 × 0.5) = Rs. 705.6
