[chunsj]

Why should we take the meaning of revolution in this problem not as the contacting point to meet the circle again, but just as the pointing the same direction? I think this is the source of confusion here.

I'm not the native speaker of English and I might take the meaning of "revolution" very absurdly here. Just curious and I have to ask this. :-)

[scotty79]

He mentions that the word revolution has specific meaning in astronomy which doesn't make any sense in the context of this problem.