Question
Without using tables, verify that:
$\cos 60^{\circ}=\frac{1-\tan ^2 30^{\circ}}{1+\tan ^2 30^{\circ}}=\frac{1}{2}$.
$\cos 60^{\circ}=\frac{1-\tan ^2 30^{\circ}}{1+\tan ^2 30^{\circ}}=\frac{1}{2}$.
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Answer
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