Wolfram Technology Guide: Dynamic Interactivity  previous | next 
Use Any Number of Controls
Mathematica lets you immediately introduce any number of controls.
In[1]:=

Click for copyable input
Manipulate[

 Graphics[{Opacity[.75, Red], 

   Table[Disk[Sqrt[i] {Sin[i (a Degree)], Cos[i (a Degree)]}, 

     size], {i, 0, n}]}, PlotRange -> Sqrt[n] + size ],

 {{n, 100, "number of disks"}, 1, 300},

 {{size, .75, "radius of disks"}, 0.1, 2},

 {{a, 137.5, "angle"}, 0, 180, Appearance -> "Labeled"}]
Out[1]=