Slice

Half the radius, times the crust.

Cut a pie into eight equal slices. Each one is an eighth of a full turn: forty-five degrees at the point.

Here is a rule for any slice. Measure from the point to the crust, then along the crust. Multiply the two and take half. That is how much pie is in the slice.

Do the same for the whole pie and you get the area of a circle, πr². The rule holds for any slice, of any pie, cut by anyone.

8 slices, laid point to crust. The row is 3.0615 radii long; thinner slices bring it to π, and the shape to a rectangle.

Figure The slices laid point to crust. The thinner they are cut, the closer the row comes to a rectangle π radii long.

“Slice.” Wondering About Pi, no. 3.1415926 (24 September 2026). wap.mom/slice/