Results 1 to 2 of 2

Math Help - Identities

  1. #1
    Member purplec16's Avatar
    Joined
    Oct 2009
    Posts
    187

    Identities

    tan^4k-sec^4 k=1-sec^2 k
    (tan^2k-sec^2k)(tan^2k+sec^2k)
    (-1)(tan^2k+sec^2k)
    -tan^2k-sec^2k
    What do i do next?
    Follow Math Help Forum on Facebook and Google+

  2. #2
    Super Member

    Joined
    May 2006
    From
    Lexington, MA (USA)
    Posts
    11,865
    Thanks
    744
    Hello, purplec16!

    There's a typo . . .


    \tan^4\!x-sec^4\!x \;=\;1-{\color{red}2}\sec^2\!x
    Then your work is correct . . .

    (\tan^2\!x-\sec^2\!x)(\tan^2\!x+\sec^2\!x)

    . . \;=\;(-1)(\tan^2\!x+\sec^2\!x)

    . . =\; -\tan^2\!x-\sec^2\!x

    . . . . =\; -(\sec^2x - 1) - \sec^2x

    . . . . =\;-\sec^2x + 1 - \sec^2x

    . . . . =\;1 - 2\sec^2x

    Follow Math Help Forum on Facebook and Google+

Similar Math Help Forum Discussions

  1. Replies: 6
    Last Post: June 23rd 2010, 12:59 AM
  2. identities..
    Posted in the Trigonometry Forum
    Replies: 3
    Last Post: July 29th 2009, 01:33 PM
  3. Identities
    Posted in the Trigonometry Forum
    Replies: 2
    Last Post: July 14th 2009, 08:58 AM
  4. identities
    Posted in the Trigonometry Forum
    Replies: 5
    Last Post: November 2nd 2008, 04:34 PM
  5. Identities
    Posted in the Trigonometry Forum
    Replies: 3
    Last Post: July 11th 2008, 04:53 AM

Search Tags


/mathhelpforum @mathhelpforum