On Mon, 31 Jan 2005 08:34:46 -0800, aiiadict wrote:
> I don't know the geometry term, but
> I want to compute which cells
> in a graph are covered by a "pie slice"
> of a circle.
In the subject line you also mention the area of the circle. I'll give
you a couple of formulae. One is more interesting than the other.
Area = Pi * r^2
Pi is a constant. It is an infinite non-repeating real number. Depending
on the level of accuracy you want you would use different approximations.
Here is a formula which gives a better approximation than is in most
calculators.
Pi = 355 / 113
An engineer friend told me the best way to remember it is doubling the
first three odd numbers (113355) and dividing the second three by the
first.
If you want to figure out the area of a pie slice, you can determine the
length of the arc and compare it to the circumference of the circle. Then
look at what percentage of the entire circumference is occupied by the
arc. Multiply the percentage by the volume of the circle and voila... You
have the area of the pie slice.
I wish they gave us interesting problems like this when I took comp. sci..
Later
Mike