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:

The semi perimeter of the each triangular shape = (28+9+35)/2 cm = 36 cm

By using Heron’s formula,

The area of each triangular shape will be

= 36√6 cm2 = 88.2 cm2

Now, the total area of 16 tiles = 16×88.2 cm2 = 1411.2 cm2

It is given that the polishing cost of tiles = 50 paise/cm2

∴ The total polishing cost of the tiles = Rs. (1411.2×0.5) = Rs. 705.6