- #1
squalho
- 11
- 0
Hello,
I have been an avid reader of the physics forum, and now I think I finally have something worth asking. The problem is engineering-related, but it all comes down to a trigonometric equation, so I'm posting in general math.
The problem is the following:
[tex]\frac{1}{N^2} \frac{\sin^2(Nx)}{\sin^2(x)} = \frac{\sqrt{2}}{2}[/tex]
I need to solve for x. N is an integer >1. I'm stuck because I don't know how to use arcsin in this case, and in most cases I would end up trying to do arcsin of something larger than 1, that doesn't make sense.
Another related problem is to find the maxima and minima (global would be the best, but local would be better than nothing) of:
[tex]\frac{1}{N} \frac{\sin(Nx)}{\sin(x)}[/tex]
Here the problem is that computing the derivative I get something that has sine and cosine with argument x and Nx, and there is no good (easy) way to simplify those sin(Nx)'s in order to get something that is a function of just x.
I can plot and find all this information with MATLAB, but I'd like to know if it's possible to find an analytical form. I have been banging my head on this for a while now, but I can't come to a solution. Any idea? Especially about the first one...
Thanks!
--
Squalho
I have been an avid reader of the physics forum, and now I think I finally have something worth asking. The problem is engineering-related, but it all comes down to a trigonometric equation, so I'm posting in general math.
The problem is the following:
[tex]\frac{1}{N^2} \frac{\sin^2(Nx)}{\sin^2(x)} = \frac{\sqrt{2}}{2}[/tex]
I need to solve for x. N is an integer >1. I'm stuck because I don't know how to use arcsin in this case, and in most cases I would end up trying to do arcsin of something larger than 1, that doesn't make sense.
Another related problem is to find the maxima and minima (global would be the best, but local would be better than nothing) of:
[tex]\frac{1}{N} \frac{\sin(Nx)}{\sin(x)}[/tex]
Here the problem is that computing the derivative I get something that has sine and cosine with argument x and Nx, and there is no good (easy) way to simplify those sin(Nx)'s in order to get something that is a function of just x.
I can plot and find all this information with MATLAB, but I'd like to know if it's possible to find an analytical form. I have been banging my head on this for a while now, but I can't come to a solution. Any idea? Especially about the first one...
Thanks!
--
Squalho