Proving Miquel's Theorem: Need Help!

  • Context:
  • Thread starter Thread starter pholee95
  • Start date Start date
  • Tags Tags
    Theorem
Join the discussion
Registration is free. Ask a follow-up in this thread, or start your own.
1 reply · 2K views
pholee95
Messages
9
Reaction score
0
I don't know how to start proving this theorem, so can someone please help? I need to prove that the circumcircles all intersect at a point M. Thank you!

Miquel's Theorem: If triangleABC is any triangle, and points D, E, F are chosen in the interiors of the sides BC, AC, and AB, respectively, then the circumcircles for triangleAEF, triangleBDF, and triangleCDE intersect in a point M.

I have attached here the figure of theorem.
 

Attachments

  • Screenshot 2016-11-21 at 11.01.41 AM.png
    Screenshot 2016-11-21 at 11.01.41 AM.png
    11.1 KB · Views: 149
Mathematics news on Phys.org
pholee95 said:
I don't know how to start proving this theorem, so can someone please help? I need to prove that the circumcircles all intersect at a point M. Thank you!

Miquel's Theorem: If triangleABC is any triangle, and points D, E, F are chosen in the interiors of the sides BC, AC, and AB, respectively, then the circumcircles for triangleAEF, triangleBDF, and triangleCDE intersect in a point M.

I have attached here the figure of theorem.
Have you looked at https://en.wikipedia.org/wiki/Miquel's_theorem? The trick seems to be to take $M$ to be the point where two of the three circles meet, draw the lines $MD$, $ME$ and $MF$, then use properties of cyclic quadrilaterals to show that $M$ also lies on the third circle.