If a rectangle has a length of 15 cm and a diagonal of 17 cm, what is the area of the rectangle?

Question: If a rectangle has a length of 15 cm and a diagonal of 17 cm, what is the area of the rectangle?

Solution:
Given that,
Length = 15 cm
Diagonal = 17 cm
Width = ?

Using Pythagoras theorem,
diagonal² = length² + width²
⇒ 17² = 15² + w²
⇒ 289 = 225 + w²
⇒ w² = 289 - 225
⇒ w² = 64 = 8²
∴ w = 8 cm

∴ Now Area = 15 × 8 = 120 cm²