Question 847873
Let width be x then the length will be 3x 

by Pythagoras theorem,
{{{x^2+9X^2= (6sqrt(10))^2}}}
{{{10x^2= 360}}}
{{{x^2 = 36}}}
x=6

length = 18, Breath = 6
Perimeter = 2(18+6)
= 48 cm