Example:
In a quadrilateral, the diagonals intersect at right angles and have lengths equal to 7 cm and 8 cm respectively. Find the area of the quadrilateral.

Solution: Area of quadrilateral = 1/2 * d_{1}d_{2}.
Given that,
d_{1} = 7cm and d_{2} = 8cm.
= 1/2 * 7 * 8
= 7 * 4
= 28 sq cm.

Directions: Read the above example carefully and answer the following questions:

Write at least 10 examples of your own.

Draw 2 different quadrilaterals, one with all sides equal and one with opposite sides equal. Draw their diagonals and measure them. Check whether their diagonals intersect at right angles.