Answer:
The distance between corner to corner is equal to √10 times the width.
D = √10*W
Explanation:
For a rectangle of length L and width W, the distance between two opposite corners can be calculated if we use the Pythagorean's theorem, where we can think on the length as one cathetus, the width as another cathetus and the diagonal as the hypotenuse.
Then the length of the diagonal is:
D^2 = L^2 + W^2
D = √( L^2 + W^2)
In this case we know that the length is 3 times the width, then:
L = 3*W
Replacing this in the equation for the diagonal we have:
D = √( (3*W)^2 + W^2) = √( 9*W^2 + W^2)
D = √( 10*W^2) = √10*√W^2 = √10*W
D = √10*W
The distance between corner to corner is equal to √10 times the width.