A triangular garden has sides 90m, 140m and 80m. A fence is to be put all around the garden. What will be the total cost of fencing at the rate of Rs 15 per metre? A 5m wide space is to be left on the one side for gate opening.

Heron's formula is credited to Heron of Alexandria (c. 62 ce) and is used to find the area of a triangle in terms of the lengths of its sides. In symbols, if a, b, and c are the lengths of the sides: Area = Square root of √s(s - a)(s - b)(s - c) where s is half the perimeter, or (a + b + c)/2.