Which of the following is/are not correct? (more than onecorrect)a)tan(x+y)= tan x + tan y/1-tan x .tan yb)cos2x = cos2x – sin2xc)sin2x = 2 tan x/ 1-tan2xd)cos3x = 4cos3x + 3cosx

Dear Anushka

A,B,C are correct.

Cracking IIT just got more exciting,It s not just all about getting assistance from IITians, alongside Target Achievement and Rewards play an important role. ASKIITIANS has it all for you, wherein you get assistance only from IITians for your preparation and win by answering queries in the discussion forums. Reward points 5 + 15 for all those who upload their pic and download the ASKIITIANS Toolbar, just a simple  to download the toolbar….

So start the brain storming…. become a leader with Elite Expert League ASKIITIANS

Thanks

Aman Bansal

Askiitian Expert

sin2x= 2tanx/1+tan²x          and cos3x = 4cos³x - 3cos x         

so c, d are incorrect answers

If understood then plz approve my answer.

answer  c,d