My math teacher challenged me to prove to him why the lines formed by the tangents are collinear. I showed him the proof off of cut the knot(https://www.cut-the-knot.org/Curriculum/Geometry/MongeDesargues.shtml) but he asked me what theorem or proof shows that O1A1||O2A2||O3A3. I had no ide and I don't see anything on that page that states why. So I was wondering if anuybody could enlighten me? Please, take your time and thanks in advance.
1. "RE: Monge via Desargues"
In response to message #0
>O1A1||O2A2
Start with drawing this two lines. (Don't draw the third circle. Reclloect that the two circles are homothetic.) Stare at the drawing for a while. An idea may occur to you.
Or search this forum for an answer to this question that was posted by a fellow whom your math teacher has asked earlier.
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