Holger Geschwindner: "Back then I have taken a piece of paper and asked myself: Is there a shot in which I am allowed to make mistakes and the ball falls through the ring anyway? Then I drew a sketch: The ball must have at least an incidence angle of 32 °, Dirk is 2.13 meters tall, his arms have a certain length, and if you know the laws of physics, you quickly come to a problem-solving."Quote from the weekly newspaper from the weekly Germany newspaper Zeit; January 15, 2004.
question: How does Holger Geschwindner come up with the minimum incidence angle of 32°? The sketches below may help you answering the question.
hint: under the assumption of the official NBA-measurements (to be checked at the offical rules page of NBA
ball circumference = 29.875 inches = 75.8825 cm
hoop diameter = 18 inches = 45.72 cm
continuative article (in German) "Mathe ist einfach ein saugutes Werkzeug" [pdf] in Mittellungen der Deutschen Mathematiker Vereinigung Herbst 2010