Yesterday I asked this question on electronics SE. The question is related to a three-phase electrical system and asks about what hypothesis should the system satisfy in order for the proof to hold true. However, the core of the question is to show that a certain geometrical property holds true for a generic triangle. I don't know how to prove/disprove such property and I already asked the question on electronics SE. Now I realize I could have asked directly about the geometrical property on Mathematics SE. Is it still ok for me to ask for the geometrical proof on Mathematics SE and then post the electrotechnical answer on Electronics SE or is it considered question duplication?
EDIT: The idea behind posting on Mathematics SE is that here there should be people more expert on Mathematical/Geometrical proofs than on Electronics SE where we focus more on applications.