Results 1 to 3 of 3

Math Help - Prove trig identities Help !!

  1. #1
    Newbie
    Joined
    Nov 2009
    From
    Grimsby, England
    Posts
    24

    Prove trig identities Help !!

    hi everyone, im new

    ive been stuck on these two questions for a while and was wondereing if anyone can help,
    these are the proof identity questions..

    1) secx / tanx + cotx = sinx

    2) (cosx / sinx + 1) + (sinx + 1 / cosx) = 2secx

    thanks..
    Follow Math Help Forum on Facebook and Google+

  2. #2
    MHF Contributor
    skeeter's Avatar
    Joined
    Jun 2008
    From
    North Texas
    Posts
    12,134
    Thanks
    1013
    Quote Originally Posted by mike--1988 View Post
    hi everyone, im new

    ive been stuck on these two questions for a while and was wondereing if anyone can help,
    these are the proof identity questions..

    1) secx / tanx + cotx = sinx

    2) (cosx / sinx + 1) + (sinx + 1 / cosx) = 2secx

    thanks..
    \frac{\sec{x}}{\tan{x}+\cot{x}} \cdot \frac{\tan{x}}{\tan{x}} =

    \frac{\sec{x}\tan{x}}{\tan^2{x}+1} =

    \frac{\sec{x}\tan{x}}{\sec^2{x}} =

    \frac{\tan{x}}{\sec{x}} =

    \frac{\sin{x}}{\cos{x}} \cdot \frac{\cos{x}}{1} = \sin{x}
    Follow Math Help Forum on Facebook and Google+

  3. #3
    Banned
    Joined
    Nov 2009
    From
    Lebanon
    Posts
    26
    (cosx / sinx+1 ) + (sinx + 1 / cos x )
    1. make common doniminator , then u will get :
    ( (cosx)^2 + ( sinx + 1 )^2 ) / (( sinx + 1 )cosx ) =

    ( (cosx)^2 + (sinx)^2 + 2 sinx + 1 ) / (( sinx + 1 )cosx ) =

    ( 2 + 2 sinx ) / (( sinx + 1 )cosx ) =
    2 ( 1 + sinx ) / (( sinx + 1 )cosx ) =
    2/cosx = 2 secx.
    Follow Math Help Forum on Facebook and Google+

Similar Math Help Forum Discussions

  1. Can't prove these identities?
    Posted in the Trigonometry Forum
    Replies: 6
    Last Post: November 20th 2010, 08:07 AM
  2. Using y''+y=0 to prove trig identities
    Posted in the Differential Equations Forum
    Replies: 0
    Last Post: March 16th 2010, 11:59 AM
  3. Trig Identities - Simplify and Prove
    Posted in the Trigonometry Forum
    Replies: 3
    Last Post: December 7th 2008, 03:14 PM
  4. Help Prove trig identities
    Posted in the Trigonometry Forum
    Replies: 2
    Last Post: November 4th 2008, 04:13 PM
  5. trig - prove identities
    Posted in the Trigonometry Forum
    Replies: 2
    Last Post: November 4th 2008, 01:11 PM

Search Tags


/mathhelpforum @mathhelpforum