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!

Homework Help: Proving Trig Identities

  1. Oct 22, 2006 #1
    hey guyz...ok iv been trying to figure this question out for so long...and i jus can't.i get up to a certain point and then i jus get confused.so if anyone can help me that would be great!

    Prov that:
    Cos^2x + Cotx ÷ Cos^2x – Cotx = Cos^2x (tanx) + 1 ÷ Cos^2x (tanx) -1
  2. jcsd
  3. Oct 22, 2006 #2
    [tex] \frac{\cos^{2}x + \cot x}{\cos^{2}x-\cot x} = \frac{\cos^{2}x(\tan x)+1}{\cos^{2} x(\tan x) -1} [/tex]

    Convert the left side to sines and cosines:

    [tex] \frac{\cos^{2}x + \frac{\cos x}{\sin x}}{\cos^{2}x - \frac{\cos x}{\sin x}} = \frac{\cos^{2}x\sin x + \cos x}{\sin x}\frac{\sin x}{\cos^{2}x\sin x - \cos x} = \frac{\cos^{2}x\sin x + \cos x}{\cos^{2}x\sin x - \cos x} = \frac{\cos^{2}x(\sin x + \frac{1}{\cos x})}{\cos^{2}x(\sin x - \frac{1}{\cos x})} [/tex].

    Can you go from there?
    Last edited: Oct 22, 2006
  4. Oct 22, 2006 #3
    umm ok the first setp i got...but the 2nd one im a little bit confused as to what you did...
  5. Oct 23, 2006 #4


    User Avatar
    Staff Emeritus
    Science Advisor
    Gold Member

    Note that;

Share this great discussion with others via Reddit, Google+, Twitter, or Facebook