MHB Inscribed circle in the triangle

Click For 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.
Mathick
Messages
23
Reaction score
0
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.
 
Mathematics news on Phys.org
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.
 
Here is a little puzzle from the book 100 Geometric Games by Pierre Berloquin. The side of a small square is one meter long and the side of a larger square one and a half meters long. One vertex of the large square is at the center of the small square. The side of the large square cuts two sides of the small square into one- third parts and two-thirds parts. What is the area where the squares overlap?

Similar threads

  • · Replies 59 ·
2
Replies
59
Views
29K
  • · Replies 1 ·
Replies
1
Views
2K
  • · Replies 6 ·
Replies
6
Views
2K
  • · Replies 9 ·
Replies
9
Views
2K
  • · Replies 13 ·
Replies
13
Views
2K
  • · Replies 4 ·
Replies
4
Views
2K
  • · Replies 2 ·
Replies
2
Views
1K
  • · Replies 4 ·
Replies
4
Views
1K
Replies
1
Views
2K