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MathNet 1999 — Part 01 Question 50

Math Olympiad Vault · MathNet 1999 — Part 01

Question 50

The center of gravity of triangle $ABC$ is $G$. Let $g_{a}, g_{b}, g_{c}$ denote the distances from $G$ to the sides $a, b, c$, respectively. Let $r$ be the radius of the inscribed circle.


a) Prove that
$$
g_{a} \geq \frac{2r}{3}, \quad g_{b} \geq \frac{2r}{3}, \quad g_{c} \geq \frac{2r}{3}
$$


b) Prove that
$$
\frac{g_{a}+g_{b}+g_{c}}{r} \geq 3
$$