Question -

a straight line meets AB,BC and AC produced of ABC at D,E,F respectively.prove that midpoints of DC,AE,BF are collinear....

My try -

I suppose that P and Q are midpoints of AE and DC respectively...then I draw lots of parallel lines from them to the sides to use midpoint theorem ...but none of them works. menelaus didn't work either...

Any hints ??

  • $\begingroup$ Try calculating the areas of triangles. $\endgroup$
    – John
    Mar 24, 2020 at 12:57

1 Answer 1


This is the Newton-Gauss line. Knowing the name, you can Google for proofs on the web, including this one at Wikipedia. In case the link goes bad, here's a screen cap.

enter image description here


Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.