Good morning everyone,
I’m new to the forum and a Wolfram beginner.
I’m having troubles calculating trigonometric functions with unknowns both in and out of the brackets of trigonometric functions
eg: Cos[x] - x Sin[x]==0
I usually use Solve for polynomial equations, but neither Solve not Reduce can face these kind of problems
Can someone please help me?
Thank You
[1]: https://community.wolfram.com//c/portal/getImageAttachment?filename=Annotazione2019-02-08162206.jpg&userId=1608287
Try restricting the range of the variable:
Solve[Cos[x] - x*Sin[x] == 0 && Abs[x] < 10, x]
A little more than the problem you are trying to solve:
If you follow the SE article carefully, you will have a very nice conclusion (though you have Cotc, the argument is the same)
Therefore, you have a numerically robust way to find nth solution when n is very large:
In[1]:= n=100;
In[2]:= FindRoot[Cot[x]==x,{x,n*\[Pi]+1/(n*\[Pi])}]
Out[2]= {x->314.162}
A notebooks is attached for you to play around.
solution.nb (147 KB)
Thank you very much to both of you for your answers, they will be precious.