The side of a rhombus is 5 cm and one of its diagonal is 8 cm.  What is the area of the rhombus?

24 sq. cm

In rhombus diagonals bisect each other at right angle.

Therefore, OD = \(\frac{1}{2}\) DB = \(\frac{1}{2}\) × 8 = 4

Now, In Δ AOD;

⇒ OA² = AD² - OD²

⇒ OA² = 5² - 4² = 25 - 16 = 9

⇒ OA = 3 cm

⇒ AC = 6 cm

⇒ Area of rhombus = \(\frac{1}{2}\) AC × BD =  \(\frac{1}{2}\) 8 × 6 = 24 cm²