Question

Find angle $\theta$ for which a light ray incident at angle ${60}^{\circ }$ on the horizontal mirror becomes vertical after two successive reflections at the shown plane mirrors. Draw ray diagram forth event. ($\theta$ is angle between plane mirrors)

Answer 1

By the properties of mirror we know

${120}^{0}o-\theta =\theta -{90}^o$

${210}^o=2\theta$

$\theta ={105}^o$