To get three images of a single object, one should have two plane mirrors at an angle of $...^\circ$.

The reflecting surface of a plane mirror is vertical. $A$ particle is projected in a vertical plane which is also perpendicular to the mirror. The initial velocity of the particle is $10 \, m/s$ and the angle of projection is $60^\circ$ with the horizontal. The point of projection is at a distance $5 \, m$ from the mirror. The particle moves towards the mirror. Just before the particle touches the mirror,the velocity of approach of the particle and its image is ...... $m/s$.

The following figure shows the multiple reflection of a light ray along a glass corridor where the walls are either parallel or perpendicular to one another. If the angle of incidence at point $P$ is $30^o$,what are the angles of reflection of the light ray at points $Q, R, S$ and $T$ respectively?

$A$ plane mirror makes an angle of $30^\circ$ with the horizontal. $A$ vertical ray is incident on the mirror. What is the angle between the mirror and the reflected ray in degrees?

Two mirrors at an angle $\theta^{\circ}$ produce $5$ images of a point. The number of images produced when $\theta$ is decreased to $\theta^{\circ}-30^{\circ}$ is

$A$ girl of height $150 \,cm$ with her eye level at $140 \,cm$ stands in front of a plane mirror of height $75 \,cm$ fixed to a wall. The lower edge of the mirror is at a height of $85 \,cm$ above her feet level. The height of her image the girl can see in the mirror is (in $cm$)