We know that parallelogram is also a quadrilateral. Let us also split such a quadrilateral into two triangles, find their areas and hence that of the parllelogram. Does this agree with the formula that you know already?
Polygon ABCDE is divided into parts as shown below. Find its area of AD = 8 cm, AH = 6 cm, AG = 4 cm, AF = 3 cm and perpendiculars BF = 2 cm, CH = 3 cm, EG = 2.5 cm.
 Area of polygon ABCDE = Area of  + .........
Area of  =Â
Area of trapezium FBCH = Â
                    =Â
Area of Â
Area ofÂ
So, the area of polygon ABCDE = ........
Find the area of polygon MNOPQR if MP = 9 cm, MD = 7 cm, MC = 6 cm, MB = 4 cm, MA = 2cm. NA, QC, QD and RB are perpendiculars to diagonal MP.
Area of polygon MNOPQR
=Â
∵       Area of  =Â
                      =Â
Area of trapezium ACON =Â
                   Â
                   Â
                    Â
                    Â
The shape of the top surface of a table is a trapezium. Find its area if its parallel sides are 1 m and 1.2 m and perpendicular distance between them is 0.8 m.