Results 1 to 5 of 5

Thread: Trig identity question

  1. #1
    Member highshill's Avatar
    Join Date
    Jul 2017
    HSC
    2018
    Gender
    Female
    Posts
    275
    Rep Power
    1

    Question Trig identity question

    Does any one how to solve this I know what do but keep making a mistake somewhere
    Prove:
    (sins-cosx)= sinx-cosx-2sinxcosx+2sinxcos^2x

  2. #2
    Junior Member 1729's Avatar
    Join Date
    Jan 2017
    HSC
    2018
    Gender
    Male
    Location
    Sydney
    Posts
    147
    Rep Power
    1

    Re: Trig identity question

    Quote Originally Posted by highshill View Post
    Does any one how to solve this I know what do but keep making a mistake somewhere
    Prove:
    (sins-cosx)= sinx-cosx-2sinxcosx+2sinxcos^2x
    Double-check the LHS is written correctly ('sins', and there may be an exponent because there are parentheses)

  3. #3
    Member highshill's Avatar
    Join Date
    Jul 2017
    HSC
    2018
    Gender
    Female
    Posts
    275
    Rep Power
    1

    Re: Trig identity question

    It was the LHS to the power of three sorry I typed it wrong

  4. #4
    Vexed?
    Join Date
    Sep 2016
    HSC
    N/A
    Gender
    Male
    Location
    Antartica
    Posts
    277
    Rep Power
    1

    Re: Trig identity question

    Identity is false for all integer powers (of LHS).
    Last edited by He-Mann; 14 Jul 2017 at 8:27 PM.

  5. #5
    Vexed?
    Join Date
    Sep 2016
    HSC
    N/A
    Gender
    Male
    Location
    Antartica
    Posts
    277
    Rep Power
    1

    Re: Trig identity question

    I believe there is another typo on the RHS. Expand via binomial theorem and use Pythagorean trig identities to get


Thread Information

Users Browsing this Thread

There are currently 1 users browsing this thread. (0 members and 1 guests)

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •