Hiya, I'm really curious to know the rules of combining trig functions, say if: y = sin(x) + cos(2x) _How would I determine the period of the sinusoid (if it IS one) Is there a mthod of predicting if two sinusoids will compose another sinusoid, if there is I'm missing it. My text book says that 2*pi is always a good solution to check for, but what does that mean? How do I check? In the end, I really need a better means of learning Trig, my text makes too many conjectures w/o backing any of them up. Any hyelp woudl be appreciated!