Hello to all,
This question is in my mind quite long-time ago but I do not have the answer. Every body say that when we drill a ball with 3 3/8 the ball will have a maximum flare because this position is a 45°. Mathematicaly, I can’t see this.
Just visionary 3 kinds of bowlers :
A full roller, the track of the ball will be very big and the 45° could not be at 3"3/8 of the Pap.
A Semi roller, perhaps for this kind of bowlers the leverage is in this location.
And for the spinner, the Track is very small and also the 45° point can’t be at 3"3/8 from the Pap.
Please, explain me because, it’s so confuse in my mind.
Sorry for my poor English.  

Thanks pnj1967, I already seen these sites and also read a lot of treats from LuckyLefty & others gurus in this site. I agree with the degree system but for the conversion degree : inches I can't explain it for myself.
In my mind, a 3"3/8 correspond of the 45° for some kind of bowlers and perhaps 4"xx or 2"xx correspond of the 45° for others kind of bowlers ?
While everybody say that the leverage point is 3"3/8
Help me to clarify this please.

Thanks to all, I’ll try to clarify my idea, a 0° is a position of pin in pap, I think that we all are ok with this. A 90° is a position the plan perpendicular to the axis and pass through the center of the ball, am I right? (in this way, the distance of any where from the circonference of this plan to Pap is 6 3/4. but the first track of the bowler do not always be at this distance. We can take an example of a big spinner, his ball track shall be very little and very far from his pap. I’m always confused. 90° is the position of the pin in first track or the pin position in the imaginary ring perpendicular to the axis and pass through the center