1. Feb 1, 2015 #1

   wei1006

   

   1) Question statement:
   Simplify 2sec^2x-2sec^2xsin^2x-sin^2x-cos^2x
   
   2)Relevant equations:
   tan A=sinA/cos A
   1+tan^2A=sec^A
   cot A=1/tanA
   cot A=cos A/sinA
   sin^2A+cos^2A=1
   secA=1/cos A
   cosecA=1/sinA
   1+cosec^2A= cot^2A
   sin2A=2sinAcosA
   cos2A=1-2sin^2A=cos^2A-sin^2A=2cos^A-1
   tan2A=(2tanA)/1-tan^2A
   
   3) Attempt:
   2sec^2x-2sec^2xsin^2x-sin^2x-cos^2x
   = 2sec^2x(1-sin^2x)-sin^2x-cos^2x
   = 2sec^2x(cos^2x)-sin^2x-cos^2x
   
   I am stuck after this... Will be helpful if some clues are provided. Thank you!

    

   wei1006, Feb 1, 2015
2. 
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3. Feb 1, 2015 #2

   Dick

   

   Science Advisor

   Homework Helper

   Use that sec(x)=1/cos(x).

    

   Dick, Feb 1, 2015
4. Feb 3, 2015 #3

   Brian T

   

   Also, at the end you have: (... -sin^2x - cos^2x) . What could you do with that?

    

   Brian T, Feb 3, 2015

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