1. Limited time only! Sign up for a free 30min personal tutor trial with Chegg Tutors
    Dismiss Notice
Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Trig Functions question

  1. Apr 9, 2007 #1
    1. The problem statement, all variables and given/known data

    Simplify: cosx / (1+sinx)

    2. The attempt at a solution

    1 / (sec x)(1+sin x)

    1 / (sec x + (sin x / cos x))

    1 / (sec x + tan x)

    I know that the answer is sec x - tan x but don't know how to get there.

    Any help would be appreciated.
  2. jcsd
  3. Apr 9, 2007 #2
    Do you know what the value of [tex]sec^2x-tan^2x[/tex] is?

    The difference of two squares helps too.
  4. Apr 9, 2007 #3
    sec^2 (x) - tan^2 (x) = 1

    but nothing's squared in the problem
  5. Apr 9, 2007 #4
    Not until you do some multiplying.

    Do you understand what I mean by the difference of two squares?
  6. Apr 9, 2007 #5


    User Avatar
    Science Advisor
    Homework Helper

    You could also just multiply top and bottom of your given expression by (1-sin(x)) and expand. It's really the same thing as jing is suggesting.
  7. Apr 9, 2007 #6
    OK, So it's

    (sec x - tan x) / (sec x + tan x)(sec x -tan x)

    = (sec x - tan x) / 1

    = sec x -tan x

    Thank you so much!!
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook

Similar Discussions: Trig Functions question
  1. Trig Functions . (Replies: 16)

  2. Trig function question (Replies: 4)

  3. Trig function question (Replies: 1)

  4. Trig Functions (Replies: 4)