Sorry, I'm still confused. For this example...
x(t)=4sin(15t)-3cos(9t+1.1)
...I have graphed this in MATLAB, and graphically found a period of about 2.1. I am trying to apply what you suggested, but can't figure out how to calculate the period of 2.1...
What if you have a harmonic function with both cos and sin?
such as: x(t)=4sin(15t)-3cos(9t+1.1)
can you find the period of this analytically? I have found this has a period of 2.1 by plotting it in MATLAB, but can't figure out how to calculate this analytically...