When, geometrically, do you know you have BI?

[ref2coach]

Rim diameter is 18", Ball diameter is 9". The square in question is 18" tall and 24" wide. So once about 1/4 of the ball is within the square then it has penetrated the imaginary cylinder above the basket. So yes by geometry BI could be called it the ball is contacted after the referee observes that a 1/4 or more of the ball is inside the square.

[referee99]

Originally Posted by ref2coach

Rim diameter is 18", Ball diameter is 9". The square in question is 18" tall and 24" wide. So once about 1/4 of the ball is within the square then it has penetrated the imaginary cylinder above the basket. So yes by geometry BI could be called it the ball is contacted after the referee observes that a 1/4 or more of the ball is inside the square.

but what about the flange extending the ring out away from the board? that has to make that imaginary line closer to the center of the back board.