Of course, in a real game of pool, straight shots like what we dealt with above don't happen too often. For example, suppose you're playing 8 ball and are faced with the following situation:
Figure:
A harder shot
Your opponent's 9 ball is blocking your shot to the top-right corner; the only way you're going to be able to sink the 8 ball is by banking it off the top rail and into the bottom-right corner pocket.
2.
How might we figure out in what direction to hit the 8 ball? Where should it bounce of the top rail in order to end up in the bottom-right pocket?
3.
We're trying to figure out the path the 8 ball should take, so we can safely ignore the cue ball and the 9 ball for now. Here's what we would like the 8 ball to do:
Figure:
The path we want the 8 ball to take
4.
Without using a protractor, what is the relationship between angle 8GB and angle DGC? Angle 8GB is called the angle of incidence and angle DGC is called the angle of refraction.
5.
Our goal is to figure out where G is; let's use Geometer's Sketchpad!
