Hello

I am trying to revise some rules regarding the period of sines (or cosines) when (a) they are added , and (b) they are multiplied. I haven't had too much luck Googling this topic.

For example, what would be the fundamental period of:

y=cos(2.pi.2x) + cos(2.pi.3x)

Or, if we multiply:

y=cos(2.pi.2x).cos(2.pi.3x)

People have suggested to me that I use trig. identities (or complex exponentials) but I am sure there is a more intuitive way such as considering the phases between both parts.

Any ideas appreciated !

Cheers

Gabber