Help proving a trig identity?  TOPIC_SOLVED

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Help proving a trig identity?

Postby Jiremi on Mon May 24, 2010 1:46 pm

I've been working on proving this identity for quite a while now, and I still can't seem to get it. Here's the problem:

sinx + cosx + sinxtanx + cosxcotx = secxcscx

I've tried working on both the left and the right by using every method I can think of, but I still can't prove it.
Any help will be greatly appreciated.
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Postby stapel_eliz on Mon May 24, 2010 4:04 pm

Are you sure that the right-hand side is a multiplication, and not an addition? :wink:
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Re: Help proving a trig identity?

Postby Jiremi on Tue May 25, 2010 1:41 pm

Yes, I'm quite sure. Although if it were addition, it would be a whole lot easier.
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  TOPIC_SOLVED

Postby stapel_eliz on Tue May 25, 2010 11:50 pm

I can get the left-hand side to equal sec(x) + csc(x), and since this does not equal sec(x)*csc(x), I'm wondering if there is a typo in the exercise.

Have you tried graphing the left- and right-hand sides as functions (on a graphing calculator, for instance), and seeing if the lines match up? Because that's not what I'm getting.
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Re: Help proving a trig identity?

Postby Jiremi on Wed May 26, 2010 1:46 pm

I just asked my teacher, and she told me that there indeed was a typo in the worksheet. It should be sec(x) + csc(x), just like you said it might.
Thanks for the help~
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