text: physics multiple choice question? hi everyone! i wanted to ask you a multiple choice question appearing in my exam. the question is as follows:  3 students stand 2 m apart in front of a plane mirror which is 3 m long. student y is standing opposite the mid-point of the mirror while the other 2 students are standing 2 m from him in a staight line.   the question is how many students can see the images of the other two?  a) 0 b) 1 c) 2 d) 3   only one answer is correct. please explain your answer. i try to copy the figure provided in the question as below: x and z are standing 2 m from y who is at the middle of the mirror.                    x   y z angle of incidence = angle of reflection.  this also means that a ray will hit the mirror at the midpoint between origin and destination.  so,  for y to see z the ray must hit the mirror 1 meter from it's center.  that puts it at 1/2 meter from the edge so you're ok.  by symmetry y can also see x.  also by symmetry, z can see y.  but can z see x?  the ray from x to z (and z to x) must strike the mirror at its midpoint.    so, it looks like all three can see the other two.  i think the answer is d provided:  y is standing in front of the center of the mirror, right?