Given:
Sides are 20 cm each and one diagonal is of 24 cm.
The diagonal divides the rhombus into two congruent triangles, as shown in the figure below.
We will now use Hero’s formula to find the area of triangle ABC.
First, we will find thee semiperimeter
= 192 cm2
Now,
Area of the rhombus = 2 x Area of triangle ABC = 192 x 2 = 384 cm2