Given, Diagonal of the rectangle = 65 cm One side of the rectangle = 63 cm Formula: In rectangle, (Diagonal)2=(length)2+(breadth)2 Calculation : According to the question 652=(length)2+632 ⇒ 4225=(length)2+3969 ⇒ (length)2=4225–3969 ⇒ Length = √256 ⇒ Length = 16 ∴ The longest side of the rectangle is 16.