For specular reflection of a light ray, the angle of incidence a) must be equal to the angle of reflection. b) is always less than the angle of reflection. c) is always greater than the angle of reflection. d) is equal to $90^{\circ}$-the angle of reflection. e) may be greater than, less than, or equal to the angle of reflection.

A person stands at a point $P$ relative to two plane mirrors oriented at $90.0^{\circ}$, as shown in the figure. How far away from each other do the person's images appear to be?

A periscope consists of two flat mirrors and is used for viewing objects when an obstacle impedes direct viewing. Suppose Curious George is looking through a periscope, in which the two flat mirrors are separated by a distance $L=0.400 \mathrm{~m}$, at the Man in the Yellow Hat, whose hat is at $d_0=3.00 \mathrm{~m}$ from the upper mirror. What is the distance $D$ of the final image of the yellow hat from the lower mirror?