Question 4
Let $ABCD$ be a parallelogram with $AB=2BC$ and $\angle DAB>90^\circ$. Let $M$ be the midpoint of $DC$. Choose $K$ on line $AC$ so that $\angle MKC=\angle CKB$. The circumcircle of triangle $DKM$ meets $AC$ again at $N$. Find $\dfrac{NA}{NC}$.
