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MathNet 2026 — Part 07 Question 28

Math Olympiad Vault · MathNet 2026 — Part 07

Question 28

Let $ABC$ be a triangle with center of gravity $G$. Let $D \neq A$ be a point on the line $AG$ such that $AG = GD$, and $E \neq B$ is a point on the line $GB$ such that $GB = GE$. Finally, let $M$ be the midpoint of $AB$. Prove that the $BMC D$ quadrilateral is inscribed in a circumference if and only if $BA = BE$.