Question 172
A special quadrilateral - the angles $A \widehat{B} C$ and $C \widehat{D} A$ of the quadrangle $A B C D$ of the figure are straight and the four sides of the quadrilateral measure whole numbers that are all different. If $A D=7$ and $B C=11$, how much do the sides $A B$ and $C D$ measure? 