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Converging Trig!

Geometry Level 3

\[ \large \sum_{n=0}^\infty \sin18^\circ (\cos 18^\circ)^n = \cot \beta \]

Find \(\beta^{3/2} \).

Note: \(0^\circ \leq \beta \leq 90^\circ\)

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by Dallin Richards

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