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有没有好办法？

cma 2012-01-01 09:00:01 ( reads)

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

跟帖(7)

exe

2012-01-01 13:05:10

38次？

花心鬼

2012-01-01 14:40:53

1 time deal... or... 70 times?

jinjing

2012-01-01 17:39:52

your method only in special case can be OK.

jinjing

2012-01-02 11:12:38

If it is from Ps Q, We can do like that

cma

2012-01-02 13:48:33

回复：If it is from Ps Q, We can do like that

jinjing

2012-01-02 16:54:15

dear cma,81is not good.

jinjing

2012-01-03 12:09:54

I try by strict Math, the anwser should be between 78 and 81