Question

What will be the perimeter of a rectangle if its length is $3$ times its width and the length of the diagonal is $6\sqrt{10}$cm?

Answer 1

R.E.F image

$;l=3b;d=6\sqrt{10}$

$\Rightarrow d=6\sqrt{10}=\sqrt{l^2+b^2}$

$\Rightarrow 6\sqrt{10}=\sqrt{10}b\Rightarrow b=6$

& $l=3b=18$

$\therefore$ Perimeter $=2(l+b)=48cm$