Differences between the different solve/zeros commands?

[pr0]

(10-24-2014 08:04 AM)parisse Wrote:  This equation has no solution. If you take exp(0.3*i*x), x must be in radians, therefore argument should be rescaled in -pi..pi.
fsolve(arg((-e^(-0.3*i*x))/(x^2-i*x))=-165*pi/180,x=-10..10)
returns 2 solutions.

Thanks! When is fsolve recommended and when is other commands recommended for solving? Any other cases radians must be selected?