The approximation for pi given by
(1)
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(2)
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(3)
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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)
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This construction was given by the Polish Jesuit priest Kochansky (Steinhaus 1999).