How do I get Symbolic/simplify to replace 1-cos(theta)^2 with sin(theta)^2 etc.

I am using simplify on a long, complicated symbolic expression, and it does not replace 1-cos(theta)^2 with sin(theta)^2 nor 1-sin(theta)^2 with cos(theta)^2. It does so on a trivial test expression, but not on my expression, even using 'steps', 1000. How can I force these substitutions?

Answer 1

[Star Strider]

Without having the longer expression to experiment with, perhaps rewrite or subexpr could work.