The sides of a triangular field are 120 m, 170 m and 250 m.The cost of levelling the field at the rate of ₹7.40/m² is:

₹66,600

We have,

Side of the triangle are  = 120, 170, 250

Semi perimeter = \(\frac{(120 + 170 + 250) }{2}\) = 270

Area = \(\sqrt {s(s-a)(s-b)(s-c) }\)

= \(\sqrt {270(270-120)( 270-170)( 270-250) }\)

= \(\sqrt {270(150)( 100)( 20) }\)

= 9000 m²

The cost of leveling the field at the rate of ₹7.40/m² is = 9000 ×7.4 =  ₹66,600