Physics homework help: lasers and mirrors?

Question

My physics teacher doesn't teach us much. I don't know how to do this problem. I hate having others do my homework, but I don't know how to do it. Thanks.

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Answer 1

public urination is just wrong

Answer 2

nothing to do with lasers but an amusing little problem

requiring a simple bit of trigonometry to solve.

Theta is the exterior angle of a triangle

= twice 1st incident angle + twice 2nd incident angle      

(I mean incident angles with the vertical to the mirror)

Now look at the triangle with the 50deg + (90-1st incident) + (90-2nd incident) = 180deg  

so 1st + 2nd = 50deg so twice that is 100deg.

Bingo!