First if the centroid and circumcentre coincide, prove that the triangle is equilateral. So:Given: , and are the mid-points of andSecond we prove that if a triangle is equilateral, then the centroid and circumcentre coincide. Do this using congruent triangles to prove that each median makes an angle of with the opposite side. Can you complete this now?
In :(given)are congruent. SSS.