Geometry Of Pool

Important To Mastering Aiming

Geometry is CRUCIAL in becoming a good billiards player. Every single stroke of the game is connected to geometry. You need to understand angles and how they relate to one another to find out where to aim to hit the ball. You need to know geometry to calculate where the ball will be after your shot is over. You need to know Geometry to successfully use the bank to pocket a ball. So we are going to explain a little bit about geometry, that way you can improve your pool game.

There are many shot strategies that make use of geometry in billiards andyou will use them in every game. For instance, the Cut Shot is a major pool Shooting technique you need to master as the it is involved in almost every shot.

You will use a cut shot when the line created by the cue ball and the object ball is not linear with the pocket. Your goal with a cut shot is for the cue ball to impact the object ball creating a line to the side of the object ball opposite the pocketís target line. The picture right depicts such a cut shot into the corner pocket.
The critical geometry lesson you need for a good cut shot is to understand the relationship between billiards balls which are perfect spheres, the aiming point and the contact point.

Point vs Aiming Point

I have never run across a clearer explanation of this relationship in the billiards aiming process than the one presented by Ewa Mataya Laurence in her "Complete Idiot's Guide to Pool and Billiards":

"Because this concept is so important, I've decided to break the procedure into a list of steps so you can clearly see how to establish the aiming point and contact point of any cut shot (almost any shot, remember, is a cut shut)," wrote the Striking Viking.

The drawing at the left illustrates the list of steps she outlines below. To make it clearer, we have colored the contact point gray and the aiming point in red.

Realize that the aiming point you are setting up here is the center of the "Ghost Ball immediately adjacent to the cue ball centered on the target line to the pocket. Your object is to replace the Ghost with your cue ball to hit the correct contact point.

The steps she enumerated are:
  1. Put the cue ball and a numbered ball on the table a couple inches apart.
  2. With your hand, slide the cue ball straight into the numbered ball and notice how small an area of the balls actually meets.
  3. Return the balls to their original positions. This time, slide the cue ball into the numbered ball in such a way that it (object ball) heads off in a near 45-degree angle. Notice that the point of contact between them is in a different position than when the two balls met in the straight hit.
  4. Repeat the process a third time, this time notice the imaginary line through the cue ball aimed directly at the contact point in step 4 that produced the 45-degree angle "shot".
  5. By aiming the imaginary line at the contact point on the object ball and sliding the cue ball to it, you will notice the cue ball actually hits it in a different place. That is because both balls are round.
When aiming at a ball, the kind of shot that one needs to make is dependent on the aim. To aim with precision, more than common sense is needed. Normally, when a ball is hit head on the ball will roll in such a way that it will follow the same path taken by the cue ball.

There are several things that one needs to take into consideration when aiming at a ball. You must remember where the cue ball will end up to be a good player. Some factors that change this are the force that the cue ball is hit with, the spin of the cue ball, (determined by where the cue stick hits the ball) and the speed and magnitude of both balls.