有沒有好辦法？

來源: 於 2012-01-01 09:00:01 [舊帖] [給我悄悄話] 本文已被閱讀：次

A beam of light strikes \overline{BC}\, at point C\, with angle of incidence \alpha=19.94^\circ\, and reflects with an equal angle of reflection as shown. The light beam continues its path, reflecting off line segments \overline{AB}\, and \overline{BC}\, according to the rule: angle of incidence equals angle of reflection. Given that \beta=\alpha/10=1.994^\circ\, and AB=AC,\, determine the number of times the light beam will bounce off the two line segments. Include the first reflection at C\, in your count.

AIME 1994 Problem 14.png