The approximation for pi given by
 |  |  |
(1)
|
 |  |  |
(2)
|
 |  |  |
(3)
|
In the above figure, let 
, and construct the circle centered at 
of radius 1. This intersects 
at point 
.
Now construct the circle about 
with radius 1. The circles 
and 
intersect in 
, and the line 
intersects the perpendicular
to 
through 
in the point 
.
Now construct the point 
to be a distance 3 along 
. The line segment 
is then of length
 |
(4)
|
This construction was given by the Polish Jesuit priest Kochansky (Steinhaus 1999).
