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7

The perimeter of a triangular field is 540m and its sides are in the ratio 25 : 17 : 12. Find the area of the triangle. Also, find the cost of ploughing the field at Rs. 18.80 per 10m^{2}.

Let the sides of the given triangle be 25x, 17x and 12x

Given,

Perimeter of the triangle = 540 m

540 = 25x + 17x + 12x

540 = 54x

x =

x = 10 m

Thus, sides of the triangle are:

25x = 25 × 10 = 250 m

17x = 17 × 10 = 170 m

12x = 12 × 10 = 120 m

Let,

a = 250 m, b = 170 m and c = 120 m

Therefore,

s =

=

=

= 270 m

Therefore,

Area of triangle=

=

=

= 3 × 3 × 10 × 10 × 10

= 900 m^{2}

Cost of ploughing the field at the rate of Rs. 18.80 per 10 m^{2} =

= Rs. 16920

Therefore, cost of ploughing the field is Rs. 16920