Question 1189850
There ia no flaw . The answer is obvious 4, length 3 width

Let diagonal be x 
Length will be (x-1)

Width will be (x-2)

(x-1)^2+(x-2)^2=x^2
Simplify 

x^2-2x+1+x^2-4x+4 =x^2
x^2-6x +5 =0
(x-5)(x-1)=0
x=5 
x cannot be 1