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MathNet 2005 — Part 02 Question 116

Math Olympiad Vault · MathNet 2005 — Part 02

Question 116

Let $\alpha$, $\beta$ and $\gamma$ be three angles with $0 \leq \alpha, \beta, \gamma \lt 90^\circ$ and $\sin \alpha + \sin \beta + \sin \gamma = 1$. Show that
$$
\tan^2 \alpha + \tan^2 \beta + \tan^2 \gamma \geq \frac{3}{8}
$$