I am having trouble simplifying this identity [cos4x= 2cos^2 2x-1]. I thought I could solve it with the double angle identity, but the 2x seems to be getting in the way. Can I remove the 2x and multiply it by the identity cos2x?
Last edited by Sedgewick19; May 18th 2010 at 02:09 PM.
Reason: misspell
I am having trouble proving this identity [cos4x= 2cos^2 2x-1]. I thought I could solve it with the double angle identity, but the 2x seems to be getting in the way. Can I remove the 2x and multiply it by the identity cos2x?