MHB Inscribed circle in the triangle

AI Thread Summary
The discussion focuses on proving that the heights of triangle PQD intersect at the incenter I of triangle ABC. The participants explore the relationship between triangle sides and their bisectors, specifically how the line AI intersects segment BC at point D. A diagram is requested to clarify the geometric relationships, and one participant provides a detailed construction involving perpendicular bisectors and intersections. The proof hinges on demonstrating that angle BH_QD is a right angle, confirming that the orthocenter of triangle PDQ is indeed point I. This geometric configuration illustrates the properties of inscribed circles and triangle centers.
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In the triangle a point $$I$$ is a centre of inscribed circle. A line $$AI$$ meets a segment $$BC$$ in a point $$D$$. A bisector of $$AD$$ meets lines $$BI$$ and $$CI$$ respectively in a points $$P$$ and $$Q$$. Prove that heights of triangle $$PQD$$ meet in the point $$I$$.

I've tried to show that sides of triangle $$PQD$$ are parallel to sides of triangle $$ABC$$ but it didn't work out. That's why I ask you for help.
 
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Can you provide a diagram?
 
I am convinced the OP has posted a true statement. I can't prove it, but hope someone here can. Here's a diagram.

1hug6x.png


Give a triangle ABC, let I be the incenter of the triangle (the intersection of the angle bisectors at A, B and C). Let D be the intersection of AI with BC and line L the perpendicular bisector of AD ($H_D$ is the midpoint of AD). Let P be the intersection of CI with L and Q the intersection of BI with L. Then the orthocenter of PDQ is I.

Clearly, if $H_Q$ is the intersection of BI with DP, it is sufficient to show angle $BH_QD$ is a right angle.
 
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