Question

Where do I start to prove this identity:
sinx/cosx= 1-cos2x/sin2x

please help!!


Hint: Fractions are evil. Get rid of them.


Well, cos2x = cos<sup>2</sup>x - sin<sup>2</sup>x, so
1-coscx = 1 - cos<sup>2</sup>x - sin<sup>2</sup>x =
1 - cos<sup>2</sup>x + sin<sup>2</sup>x
You should be able to simplify this to 2*something squared.
The denominator is sin2x = 2sin(x)cos(x)
You should be able to finish this, if not post a question.


The second line should be
1 - cos2x = 1 - (cos<sup>2</sup>x - sin<sup>2</sup>x)
then the 3rd line will make sense.
1 - cos<sup>2</sup>x should look familiar.

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