Hi,

I hope someone can help. I'm trying to rewrite the trig ratio cos3x to fit within a double angle formula. These are the steps which I have followed: https://www.algebra.com/algebra/home...on.182274.html

While I understand the steps listed in the link that I pasted above, it does not provide me with the solution that I'm looking for. The solution for this problem according to my textbook is 2cos^2(1.5x-1).

Any ideas on how to solve this problem in order for it to match up with the textbook's solution?

Sincerely,

Olivia