A triangular park `ABC` has sides `120 m, 80 m` and `50 m.` A gardener Dhania has to put a fence all around it and also plant grass inside. How much area does she need to plant? Find the cost of fencing it with barbed wire at the rate of `Rs 20` per metre leaving a space `3 m` wide for a gate on one side.

Explanation

Length of fence=perimeter of Triangle-`3m`

`=50+80+120-3`

`=247m`

Cost of wire=length`xx`cost

`=247xx20`

`=Rs.4940`

Herons formula

area=`sqrt(s(s-a)(s-b)(s-c))`

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