This tool calcs domain and range of every function: trigonometrics functions, function with sin and cos and so on. Just type ƒ(x) and let Mathematikoi calcs for you. You can type every function: this app will use the proper methods..
In order to use this app, remember to put numerator and denominator among brackets and to use ^ if you want to raise something, as in y=(2x^2-3)/(6x+8).
Mathematikoi offers also a very good plotter!.
Give it a try, it's free!.