Question

How many images of himself does an observer see if two adjacent walls and the ceiling of a square floor room are mirror surfaced?

Answer 1

If two mirrors are placed at an angle Ф, number of images would be

$n_1=\frac{360}{\Phi }-1$

For the two adjacent mirrors on walls,

$n_1=\frac{360}{90}-1=4-1=3$

For one mirror on wall and other on ceiling,

$n_2=\frac{360}{90}-1=4-1=3$

For another mirror on wall and other on ceiling,

$n_3=\frac{360}{90}-1=4-1=3$

Total images $=3+3+3=9$ images.