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MathNet 2026 — Part 05 Question 34

Math Olympiad Vault · MathNet 2026 — Part 05

Question 34

Let $ABC$ be a triangle whose side lengths are, as usual, denoted by $a = |BC|$, $b = |CA|$, $c = |AB|$. Denote by $m_a$, $m_b$, $m_c$, respectively, the lengths of the medians which connect $A$, $B$, $C$, respectively, with the centres of the corresponding opposite sides.


a. Prove that $2m_a \lt b + c$. Deduce that $m_a + m_b + m_c \lt a + b + c$.


b. Give an example of
i. a triangle in which $m_a \gt \sqrt{bc}$;
ii. a triangle in which $m_a \le \sqrt{bc}$.