I have a question. Is there any method to simplify or approximate this formula? I have never studied two trigonometric functions used at the same time, so I don't know how to approach this right now.
Formula is following:
$$\exp(-\cot(\arcsin(\frac{RS^2-RE^2}{2*r*RE} - \frac{r}{2*RE}))) $$
Here RS and RE is just constant, actually RE is radius of earth and RS is a circular orbit which is always larger than $RE (RS>RE)$. only 'r' is variable here. To be very precise, 'r' is only definable for $[R_{\min},R_{\max}]$ but I don't think this is important right now.
The problem is as I wrote, I don't have any clues or ideas to simplify/approximate this formula. Only thing I know is that the formula inside $\arcsin$ is always 0~1.
Can someone give me a hint for this? I would appreciate it very much.