Re: More trigonometric equations!!!

On Jan 31, 3:09 am, Albert <albert.xtheunkno...@xxxxxxxxx> wrote:
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?

Substituting tan(x) for u:

tan(x) / sqrt(1 + tan^2(x))
= [sin(x)/cos(x)] / sqrt(sec^2(x))
= [sin(x)/cos(x)] / sec(x)
= [sin(x)/cos(x)] / [1/cos(x)]
= sin(x)

I'll bet that you can do the other one now.

Dave
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