Shot Line

Definition

The shot line is the line at which the object ball will travel after the cue ball strikes it. This can mean the line from the center of the pocket to the object ball, or sometimes from a rail, or other object ball. You're not always trying to pocket a ball on every shot, but there is always a shot line.

Tangent Line is derived from this

The tangent line is always derived from the shot line, because this is the point of contact between the cue ball and object ball.