[1-tan^2(x/2)] / [1+tan^2(x/2)] = cosx

I don't want to bother you, but do you know of any trig identity site that discusses the rules of sin or cos or tan of (x/2)?

thanks

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- May 21st 2007, 07:47 PMMr_Greenidentity another
[1-tan^2(x/2)] / [1+tan^2(x/2)] = cosx

I don't want to bother you, but do you know of any trig identity site that discusses the rules of sin or cos or tan of (x/2)?

thanks - May 21st 2007, 07:58 PMThePerfectHacker
- May 21st 2007, 08:01 PMMr_Green
don't you want to change the more complex side into a simplified state? is there a specific rule or is that jsut my teacher's preference?

- May 21st 2007, 08:02 PMThePerfectHacker