(adsbygoogle = window.adsbygoogle || []).push({}); 1. The problem statement, all variables and given/known data

Prove that:

(1-tanθ)/(1+tanθ)=(cotθ-1)/(cotθ+1)

2. Relevant equations

Trig Identities:

tanθ= sinθ/cosθ

cotθ= cosθ/sinθ

1+tanθ=secθ

1+cotθ=cosecθ

3. The attempt at a solution

These sorts of equations are coming up a lot and I am having trouble understanding what I have to do exactly, I have seen people cross multiply which cannot really work considering we haven't got proof that they equal each other and hence can't cross multiply. I have also attempted changing 1+tanθ to secθ and 1+cotθ to cosecθ but I am having no luck. I know there is a certain way to do it, I am just unsure of what this way is.

If possible could someone give me a guide on how to do it rather than just hint at things? I am coming up to exams in about two weeks and I don't have time to muck around, I need to make sure that I know everything that could be on the test.

Thanks in advance for your inputs!!

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# Homework Help: Proving trigonometric identities

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