WHAT IS THE AREA OF AN N-SIDED IRREGULAR POLYGON? The typical way to measure the area of a piece of land with straight-line boundaries is to note the 2D coordinates [xn,yn] of the corners connecting neighboring lines. Thus if we have an irregular three sided area having corners at [0,0], [2,3] and [1,4], the side-lengths are Surface area of a box. The surface area formula for a rectangular box is 2 x (height x width + width x length + height x length), as seen in the figure below: Since a rectangular box or tank has opposite sides which are equal, we calculate each unique side's area, then add them up together, and finally multiply by two to get the total surface area. Finding area using given sides: Examples : Input : a = 5, b = 7, c = 8 Output : Area of a triangle is 17.320508 Input : a = 3, b = 4, c = 5 Output : Area of a triangle is 6.000000 Area of a triangle can simply be evaluated using following formula.