Consider a triangle \triangle{ABC}, its Incircle, \psi, and its B-mixtilinear incircle, \omega. Let T be the point of tangency of \psi and \omega. Let K and L be the points of tangency of \omega with the sides AB and BC, respectively. Call D the point of tangency of \psi with AC. Call E the second intersection (further to B) of \psi with BT. Call F the second intersection of the circumcircle of \triangle{EDI} with BT. Prove that K, F and I are collinear.
Proof. \angle{ATI}=\angle{CTI} and \angle{ATB}=\angle{CTD} (well-known). We have \angle{BTD}=\angle{ATC}-\angle{ATB}-\angle{CTD}. Notice that \angle{ATB}=\angle{CTD}=\angle{ACB} and \angle{ATC}=180^\circ-\angle{ABC}, then, \angle{BTD}=\angle{BAC}-\angle{ACB}. Moreover, TI is an angle bisector of \angle{BTD}, therefore, D is the reflection of E around TI, which means TE=TD. Said this, and having in mind that EDIF is cyclic, we find \angle{DIF}=\frac{\angle{ABC}}{2}+\angle{ACB}.
On the other hand, K, I and L are collinear (well-known), consequently, \angle{AKL}=\angle{AKI}=90^\circ+\frac{\angle{ABC}}{2}. Finally, some angle chase in quadrilateral AKID give us \angle{DIK}= \frac{\angle{ABC}}{2}+\angle{ACB}. As \angle{DIF}=\angle{DIK}, we are done.
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