Q1 of 36 Page 117

Find the cost of laying grass in a triangular field of sides 50 m, 65 m and 65 m at the rate of Rs 7 per m2

a = 50, b = 65, c = 65

s = (a + b + c)/2


⇒ s = (50 + 65 + 65)/2 = 180/2 = 90.


Area(Δ) = √s(s-a)(s-b)(s-c)


⇒ Area(Δ) = √90(90-50)(90-65)(90-65)


⇒ Area(Δ) = √90×40×25×25


⇒ Area(Δ) = 1500m2


Cost of laying grass = Area(Δ)×Cost per m2


⇒ Cost of laying grass = 1500×7 = Rs.10500


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