Trignometric identities - Prove that the following is an identity.
Hello, I am having troubles with a question involving trigonometric identities. I have always had trouble with these types of problems, so I need as much help as possible.
To the problem:
"Prove that the following is an identity: "
Here is my attempt:
I don't know what to do from here. On the left hand start I can't see where to even start. Any help at all is very much appreciated. I really do not understand these problems.