Re: More trigonometric equations!!!

Passerby wrote:
If we let  u = tan(x)  and express sin(x) and cos(x) in terms of u,
we find that

   sin(x) = u/sqrt(1+u^2)   and   cos(x) = 1/sqrt(1 + u^2)

What trigonometric identies did you use to derive this?
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