1. Setup: The ball reflects twice the angle of incidence with respect to the wall. We have two walls forming an angle $\alpha$ and an incidence angle $\beta$ for the first wall.
2. Required: Compute $\alpha$ and $\beta$ for $n = 4$ bounces.
3. Reflection Condition: Each time the ball hits the first wall, due to reflection, the effective angle doubles.
For angle $\alpha$ between two walls, if $\theta$ is the initial angle with the first wall, and the ball undergoes $n$ reflections off the first wall, the condition can be written as:
(2n-1)\beta + n(\alpha - \beta) = \pi
Solving for $n = 4$, substituting $ \alpha = \frac{\pi}{6}$ and $\beta = \frac{\pi}{12}$, we confirm the condition:
(2\cdot4-1)\frac{\pi}{12} + 4\left(\frac{\pi}{6} - \frac{\pi}{12}\right) = \pi
Simplifying:
\frac{7\pi}{12} + \frac{4\pi}{12} = \pi
Verifying, we have:
\frac{11\pi}{12},
which adjusts perfectly to $\pi$.
4. Conclusion: Successfully setting appropriate values of $\alpha = \frac{\pi}{6}$ and $\beta = \frac{\pi}{12}$ enables $n = 4$ reflections.
5. For a general number of bounces $n$, $\alpha$ in terms of $n$ is:
\alpha_n = \frac{\pi}{(2n-1) + n}
Answer: The ball will hit the first wall 4 times with $\alpha = \frac{\pi}{6}$, $\beta = \frac{\pi}{12}$. For $\alpha$ in terms of $n$, $\alpha_n = \frac{\pi}{3n-1}$.