Question

cosA=1/2 then find
tan2A=?​

Answer 1

$\cos(a) = \frac{1}{2} \\ \\ \cos(60) = \frac{1}{2} \\ \\ so \: \cos(a) = \cos(60) \\ a = 60$

Now,

$\tan2a \\ = \tan2(60) = \tan(120) = - \sqrt{3}$