This applet demonstrates a (not particularly good) way to estimate the
value of Pi: by calculating the perimeter-to-diameter ratio of an
n-sided regular polygon (which becomes a circle as n
approaches infinity).
Use the slider to set the value of n; the n-sided
polygon is shown and the corresponding approximate value of Pi.
Note that since the drawn polygons become more difficult to
distinguish from one another as n grows, the slider works on a
logarithmic scale.
Source code: The main file Pi.java, and a
supporting class nGon.java for manipulating
n-sided regular polygons.