Question

The diagonal of a rectangle $\sqrt{41}cm$ and its area is 20 sq. cm. The perimeter of the rectangle must be:

• A. 9 cm
• B. 18 cm
• C. 20 cm
• D. 36 cm
• E. 60 cm

Answer 1

The correct option is B

18 cm

$\sqrt{l^2+b^2}=\sqrt{41}or{l}^2+b^2=41.$ Also, lb = 20 (l + b)${}^2$= (l${}^2$+b${}^2$) + 2lb = 41 + 40 = 81 $\Rightarrow$ (l + b) =9 $\therefore$Perimeter = 2 (l+b) = 18 cm