i was wondering if ANYONE could help me with some proofs i missed a couple days of trig. and im totally lost so here they are

1. 1-cos(2a)/sin(2a)=tana

2. cos(2a)= 1-tan^2a/1+tan^2a

3. tan(2a)= 2/cota-tana

thanks in advance

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- May 3rd 2009, 09:33 AMbkstudent14Help needed on trigonometric proofs
i was wondering if ANYONE could help me with some proofs i missed a couple days of trig. and im totally lost so here they are

1. 1-cos(2a)/sin(2a)=tana

2. cos(2a)= 1-tan^2a/1+tan^2a

3. tan(2a)= 2/cota-tana

thanks in advance - May 3rd 2009, 10:01 AMrunning-gag
- May 3rd 2009, 10:30 AMrunning-gag