Question

cos4A= sin 2A find the value of tan 4A​

Answer 1

$tan 4a = \sqrt{3} \\ \\ \cos(4a) = \sin(2a) \\ \sin(90 - 4a) = \sin(2a) \\ 90 - 4a = 2a \\ 6a = 90 \\ a = 15 \\ \tan(4a) = \tan(60) \\ = \sqrt{3}$