Question

A triangular park ABC has side 100cm, 60cm and 80cm. A gardener 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 50 per meter leaving a space 5m wide for a gate on one side.

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Answer 1

Area.

Using Heron's formula to calculate the area, first calculate the semi-perimeter;

= (100 + 60 + 80) / 2

= 120 m

Area =
`√(120 * (120 - 100)(120 - 60)(120 - 80))`

=
`√(5,760,000)`

= 2,400 m²

Cost of fencing.

Perimeter = 100 + 60 + 80 = 240m

Less space for gate = 240 - 5 = 235m

Cost = 235 * Rs 50 per meter

= Rs 11,750

The different units used in your question would lead to an incomprehensible answer so I used meteres for all.