Question

How do you prove `(cos W - sin2W) / cos(2W) + sinW-1 = cot W`?

Answer 1

These two identities are not equal:

Graph of `(cosW-sin2W)/cos(2W) +sinW - 1`
graph{(cosx-sin2x)/cos2x+sinx-1 [-42.54, 37.46, -10.2, 29.8]}

Graph of `cotx`
graph{cotx [-42.54, 37.46, -10.2, 29.8]}