Alpha 15 grad, cos 15 grad = ??
\(cos 15°=0,965925826289\)
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\(\begin{array}{|rcll|} \hline \cos(15^{\circ}) \\ &=& \tfrac14 \cdot (\sqrt{6}+\sqrt{2}) \\ &=& 0,96592582629 \\ \hline \end{array}\)
