Hi,

I have a calculation where I have to simplify some trogonometric terms. I did it up to here und and to here I am sure that it es correct but now I stumble. How to go on?

Target of the calculation is:

This is the point I stumble:

Whats next?

I guess I have to use that sin square plus cos square is one, but I guess here it would be wrong.

thanks

greetings