Question 17
$ABC$ is acute and isosceles at A on circle $\left(O\right)$. $D$ lies on minor arc $BC$ with $DB \lt DC$. Lines through $B , C$ parallel to $AD$ meet $\left(O\right)$ at $E , F$. $K$ lies inside minor arc $AE$; $M = KE \cap AC , N = KF \cap AB$. Prove $MN , KD , BC$ concur.