Two mirrors inclined at angle θ to each other . A ray incident parallel to one of the mirror retrace its path after third reflection , then θ is

1) 45

2) 30

3) 60

4) All of these

Dear mayank

Dear mayank

at third time when ray falls on mirror it should be perpendicular then only it will retrace its path

so   3θ = 90

     θ =30

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