台球桌面上有许多的数学问题,这些问题大多又与角有关,不信请看图1,打台球时选择适当的方向用其中的一个球去击另一个球,使另一个球经过反弹后能直接入袋或经过若干次反弹后再入袋,现在我们把图1改画成如图2的平面图形,则有∠1=∠2． There are many mathematical problems on the table of billiards. Most of these problems are related to the horns. If you don’t believe them, please look at Figure 1. When playing billiards, select the appropriate direction and use one of the balls to hit another ball so that the other ball can be directly Into the bag or after a number of rebound and then into the bag, and now we change Figure 1 to a plane figure as shown in Figure 2, there is ∠ 1 = ∠ 2.