Which of the following is an identity?
sinx-cosx=tanx
(1-2sin^2x)csc^2x=4cos^2x-2
tan^2x+cot^2x=1
sin^2xcot^2x+cos^2xtan^2x=1

Question

Which of the following is an identity?
sinx-cosx=tanx
(1-2sin^2x)csc^2x=4cos^2x-2
tan^2x+cot^2x=1
sin^2xcot^2x+cos^2xtan^2x=1

directrix · Answer

@cutiecomittee123 
Have you ruled out any of the options yet?

cutiecomittee123 · Answer

Well I dont think that the first one or the third one work because just by looking at the simple identities neither of those two work.

directrix · Answer

The first one is a rip off of:  tan(x) = sin(x) / cos (x)   

It is not correct.

cutiecomittee123 · Answer

Yes I knew that. So now we have the second one and the fourth one to consider

cutiecomittee123 · Answer

I also doubt that the fourth one is equal to one therefore I dont think it is an identity.

cutiecomittee123 · Answer

since cos^2x+sin^2x=1

directrix · Answer

On the second option, is the right side 4cos^2x-2 supposed to be:

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