Question

Solve this question no. 5&6

Answer 1

$tan \: 2x \: = \: \sqrt{3 } \\ tan \: 2x \: = \: tan \: 60 \: \\ on \: comparing \: both \: sides \: \\ 2x \: = \: 60 \\ x \: = \: 30$

Answer 2

you can solve 

cos4x as

cos2(2x) =1-2sin2(2x)

             =1-2(2sinx . cosx)2                          { sin2x = 2sinx. cosx}

             =1-2(4sin2x.cos2x)

            =1-8sin2x.cos2x

LHS=RHS

question no.6 ans.
thank you