Thread by @panlepan

#Puzzle Prove that the red points are collinear.
How many proofs can you come up with ? #GeometrySnacks @edsouthall

Many solutions down there ! Here's one which is not the first one you might think of. Adding another equilateral triangle and using a 60° rotation. #MathGIF

For the colorblind folks, here's the black & white version as published in the AMS Calendar by @evelynjlamb.