Try Graphs of these sample functions
Function From To
sin(x) -PI PI
cos(x) -PI PI
sin (x*x) -PI PI
sin (x+y) -PI PI
sin (x^2) -PI PI
sin (x^0.5) -PI PI
sin (x^3) -PI PI
cos (x) * sin (x) -PI PI
cos (x+y) -PI PI
cos (x *x) -PI PI
cos (x^0.5) -PI PI
tan(x^2) -PI PI
tan(x*x) -PI PI
tan(x)*sin(x)*cos(x) -PI PI
tan(x+y) -PI PI
Graphing utilities are costly, our online graphing tools help students, teachers and professionals to make use of leading software to help visualize mathematical functions. Attending college is costly unless you happen to be on scholarship which I didn't have the privilege to thus a college drop out without a job. But that's no brain drainer, if you are going to waste time what better way to do it than to develop engineering and financial software that has gained critical acclaim amongst academia in US and UK.

GraphEasy is our brand name, although I hear people from countries that I don't want to know (Pakistan) who lay claim to my products but then they have socio cum communist system here thus the claim what I make is state's property.
Enough of wrangling, in the pane below you will find the online Java applet that will let you graph a function of x such as y = sin x 

You will find it easy to use as most elements on the calculator are self explanatory. You need to type in the function that follows a particular syntax that you can confirm with the syntax table on this page. The minimum and maximum values for x and y axis may be modified but due to the limits imposed by the dimensions of the canvas, the magnitude of the x and y axis has be lower than or equal to 300. For example, you may select MinX to be -199 and MaxX to be 100. Same goes for MinY and MaxY.

Now go ahead, graph your favorite function and see it live and best of all you can keep a copy for yourself by getting a print out for demonstration to your teacher or your students.

If the guys at Texas Instruments, or HP and Casio can design such gadgets I should be considered at par with those.

Function or Operator Function or Operator
x x Multiplication *
Addition + Division /
Subtraction - Exponentiation ^
sin x sin (x) sinh x sinh (x)
cos x cos (x) cosh x cosh (x)
tan x tan (x) tanh x tanh (x)
ln ln ex exp(x)
square root sqrt(x) x2 x^2
( ( ) )