(In reply to First part of solution
Hi Tristan. Glad to see you back.
I liked your proof, but don't think you need the lemma.
The Pythagorean theorem gives the third side.
You have probably seen the proof of the Steiner-Lehmus theorem using the above theorem. Since your proof of this theorem is direct and geometric it would seem that the proof of the Steiner-Lehmus theorem is also direct and geometric. But, John Conway does not think one exists. What do you think?
Edited on October 5, 2013, 5:03 pm
Posted by Bractals
on 2013-10-04 05:38:06