Posted by Momo on Sunday, October 18, 2009 at 1:57pm.
Solve this equation algebraically:
(1sin x)/cos x = cos x/(1+sin x)

I know the answer is an identity, and when graphed, it looks like cot x. I just don't know how to get there. I tried multiplying each side by its conjugate, but I still feel stuck. This is what I have so far:
cos^2(x)/cos x + sin x =
cos x  sin x/cos^2(x)
...but I'm not really sure how to get to the answer. Help please?
Thank you!

Math  jim, Sunday, October 18, 2009 at 2:24pm
Do you mean solve it or prove it?
It is an identity, so there really isn't a specific solution: it's true for all x.
I suggest you try reformatting as
(1sin x)/cos x  cos x/(1+sin x) = 0
Then bring both fractions to the common denominator (cosx)(1+sinx), and I think you'll recognise the numerator you're left with!

Math  Momo, Sunday, October 18, 2009 at 2:44pm
Ok, I worked it out, and so far i have this:
cos^2x  cos x  sinxcosx /
cosx + sinxcosx
Now I just need some help with reducing?

Math  jim, Sunday, October 18, 2009 at 3:01pm
Um, no. Wrong turn somewhere. It's a LOT simpler than that.
Your numerator will be :
(1sinx)(1+sinx)  cos^2x
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