I have to show that the following identity holds when 1 + cos(2Ө) does not equal 0.

tan(Ө) = sin(2Ө)/1 + cos(2Ө)

I think to do this, you'd have to use cos2Ө and sin2Ө's formulas to derive a formula for tan(Ө) or tan(2Ө). It's the (2Ө) thing that throws me off.