Draw a big enough parallelogram ABCD on a paper as shown in the figure. Draw perpendicular AE on side BC. Cut the right angled ∆AEB. Join it with the remaining part of ₹ABCD as shown in the figure.
The new figure formed is a rectangle. The rectangle is formed from the parallelogram.
So, areas of both the figures are equal. Base of parallelogram is one side (length) of the rectangle and its height is the other side (breadth) of the rectangle.
∴ Area of a parallelogram = Area of a rectangle
= length × breadth = base × height
