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Expert: - 5/6/2008


Question
I'm taking my first class in a LONG time and I'm having problems verifying this identity:

sin(2 theta) = 2 tan theta/1+tan^2 theta

Thanks,
Rob

Answer
What this looks like is sin(2t) = 2 tan(t)/1+tan^2(t).
Note that sin(2t) = 2sin(t)cos(t) and that 1+tan^2(t) = sec^2(t).  Plug these in and work away - I think you're almost near the end.  All you need now is to know that tan(t) = sin(t)/cos(t).

Have a great day!  

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