approximation of sine function

[talking]

The following represents some part of my equation, which describes sine functions in discrete domain.

y[n] = sin(2*pi*f0*n*dTs) * sin(2*pi*f0*n*Ts)

where f0 is the frequency of sine, and n variable is an integer number, n=[1:N] (e.g., N=64k).
dTs and Ts are sampling periods and they have the relationship: dTs << Ts.

Then, I have to approximate "sin(2*pi*f0*n*dTs)" among the following equation. Actually, I'm looking for a way to remove n from "sin(2*pi*f0*n*dTs)" by calculation approximation. Please help me out. This is very important for me.

 

[albbg]

Could you, please, clarify a little bit better what you exactly need ? Are you looking for a series development ?

 

[talking]

Thanks much for your interests in my question, albbg. The question has been resolved on my own. Thanks again.