r845

Let P a point on the side BC of ABC. The parallel from P to AC cuts AB at D and the parallel from P to AB cuts AC at E. Then the perpendiculars from P to DE envelope a parabola having as focus the intersection of the circumcircle with the A-symmedian, and as directrix the A-median. This parabola is tangent to BC at the intersection of BC with the orthic axis.


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