Two equilateral triangles, one upside down, have boundaries meeting at 4 points, 3 of which are marked in red. Show that the circle through the red points also passes through the centre point of the blue triangle.

Solution

Note the last angle should be angle JCK.

Two equilateral triangles, one upside down, have boundaries meeting at 4 points, 3 of which are marked in red. Show that the circle through the red points also passes through the centre point of the blue triangle. https://t.co/bJyyksd4tD By @MarshallWBuck pic.twitter.com/qD0UtzTTLB

— Mirangu (@Mirangu1) October 5, 2023