Given any expression of the form \(a\cos x + b\sin x\) it is better to rewrite it into one of the forms \(k\cos (x \pm \alpha )\) or \(k\sin (x \pm \alpha )\) before answering the question. From this ...

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 ...