Verify the identity...

label Mathematics
account_circle Unassigned
schedule 1 Day
account_balance_wallet $5

cos3x= cos^3x - 3sin^2xcosx 

Feb 1st, 2015

cos3x = cos(2x +x)

           = cos2x cosx - sin2x sinx  ,  cos(x +y) = cosx cosy - sinx siny

          = (2cos^2x - 1) cosx - (2sinx cosx) sinx  ,  using   cos2x = 2cos^2x - 1 & sin2x = 2sinx cosx

         = 2cos^3x - cosx - 2sin^2x cosx

       =      2cos^3x - cosx - 2(1 - cos^2x) cosx  ,  sin^2x = 1 - cos^2x

      = 4cos^3x - 3cosx   ,  simplify

      = cos^3x + 3cos^3x - 3cosx

     = cos^3x - 3cosx( 1 - cos^2x)  , take 3cosx common

      = cos^3x - 3cosx sin^2x  ,sin^2x = 1 - cos^2x

Feb 1st, 2015

Studypool's Notebank makes it easy to buy and sell old notes, study guides, reviews, etc.
Click to visit
The Notebank
...
Feb 1st, 2015
...
Feb 1st, 2015
Jun 26th, 2017
check_circle
Mark as Final Answer
check_circle
Unmark as Final Answer
check_circle
Final Answer

Secure Information

Content will be erased after question is completed.

check_circle
Final Answer