"Tracing" would be holding a laser in your right hand and pointing it at the Plane Line. Because the length of the laser is infinite and the club is a given length, different things are observed by the golfer. The laser light could "Trace" the line forever, but the Clubhead would visually make an arc on the ground to the inside of the Plane Line. The straight line feel of "Tracing" creates the perfect arc for the Clubhead.
In contrast, the Angle of Approach Procedure uses a very steep Plane. The new Plane Line passes through the same two points, Impact and Low Point, but the Plane angle is much steeper. Because it's steeper, the eyes see the Clubhead covering the Plane Line, instead of coming inside the Plane Line on an arc.
Hybrid Mode
