1. The problem statement, all variables and given/known data The mirror in the image below deflects a horizontal laser by angle θ. What is the angle φ if θ = 60°. 2. Relevant equations θi=θr 3. The attempt at a solution So I know that, if I draw a line normal to the mirror, that will make it so that the incident angle and the reflected angle equal 60° (since 180-60=120 and the 2 angles have to be the same, so 120/2=60) but after that, I have no idea what to do. I know the angle is 30°, but how did they get that angle. Maybe I just need to reviw my geometry.