The area of a rectangle is 20 cm². Its length is 5 cm. Find the diagonal of rectangle.

$\sqrt{41}$cm

Area of rectangle = length (l) × breadth (b)

20 = 5  × b

b = 4 cm

Diagonal of rectangle = \(\sqrt {l^2 + b^2}\)

                               = \(\sqrt {5^2 + 4^2}\)

                               = \(\sqrt {25 + 16}\)

                               = \(\sqrt {41}\)