The form you should use may be given to you in a question, but if not, any one will do. If in doubt, \(k\cos (x - \alpha )\) usually works. These worked examples show the processes you'll need to go ...

In algebra, letters are used to stand for values that can change (variables) or for values that are not known (unknowns). A term is a number or letter on its own, or numbers and letters multiplied ...