Question

The length of a rectangle is 4.5 cm and its diagonal is 5.5 cm. Find its perimeter.

Answer 1

Let ABCD is a rectangle where AB = 4.5 cm and AC = 5.5 cm

In right angled triangle ∆ABC, ∠B = 90°.

∴ From Pythagorous Theorem

BC² = AC² – AB² = 5.5² – 4.5²

= (5.5 + 4.5) (5.5 – 4.5) = 10 x 1

BC² = 10

BC= 3.16 m

∴ Perimeter of rectangle = 2(AB + BC)

= 2(4.5 + 3.16) cm

= 2 x 7.66

= 15.32 cm