- 84

- 16

Term 1:

[itex]

\left[\frac{cos(x/2)}{cos(y/2)}\right]

[/itex]

Term 2:

[itex]

\left[\frac{cos(x/2)}{cos(y/2)}-\frac{sin(x/2)}{sin(y/2)}\right]

[/itex]

I'm not sure yet if the series repeats itself or forms a pattern; but if it continues to add terms proportional to sine and cosine half angle fractions, are there any series I could use to express an infinite number of these types of terms as an exact form? I've looked at a Fourier series but I'm not sure it would work. Thank you!