#### Answer

$\tan 30=\dfrac {\sqrt {3}}{3}$

#### Work Step by Step

$\dfrac {2\tan \alpha }{1-\tan ^{2}\alpha }=\tan _{2}\alpha \Rightarrow \dfrac {2\tan 15}{1-\tan ^{2}15}=\tan \left( 2\times 15\right) =\tan 30=\dfrac {\sqrt {3}}{3}$

Published by
Pearson

ISBN 10:
013421742X

ISBN 13:
978-0-13421-742-0

$\tan 30=\dfrac {\sqrt {3}}{3}$

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