I'm reviewing for a test and I came across this problem:
I've been trying different things for about an hour, but I can't figure out how to get 2cos(x) which is the answer in the back of the book. Could anyone help me get started?
Thanks. I found the problem. In my first attempt I made a simple mistake and incorrectly derived that...
Leading to overcomplication of the problem and frustration in future attempts. Seeing it on the computer made it clear compared to my rather inconsistent handwriting.