Question

The length of a rectangle is three its width and the length of its diagonal is $6\sqrt{10}cm$, The perimeter of the rectangle is

• A. $48cm$
• B. $36cm$
• C. $24cm$
• D. $24\sqrt{10}cm$

Answer 1

Answer: (A)

$48cm$

REF.Image

Given [l=3b]

In $\Delta ABC$

$A{C}^2=b^2+l^2$

$360=10b^2$

$b^2=36$

[b= 6 cm] & [l= 18 cm]

Perimeter of rectangle = 2[l+b]

=2[6+18]

=$2\times 24$

perimeter = 48 cm