cos 2x-sin 2x 在 How to get to the other forms of the identity $\cos2x = \cos^2x 的評價 You can do it by using the Pythagorean identity: sin2x+cos2x=1. This can be rewritten two different ways: sin2x=1−cos2x. and. cos2x=1−sin2x. ... <看更多>