We can calculate the area of the simple polygons like square, rectangle, triangle, pretty easily. Area of square can be calculated by drawing it on a graph paper, of unit cm length and breadth. Area of a rectangle is length X breadth. Area of a triangle is 1/2bh, half of product of base and height. For a parallelogram , area is the product of base and height. For a trapezoid , it is 1/2(b1+b2)h. For some other extreme polygons, we can calculate the area by making it different simple polygons like square or triangle. Then add the areas of triangle and square.