When two plane mirrors are placed at some angle, multiple images of an object are formed.
The number of images formed is given by the formula N =(360θ)−1; where θ is the angle between the plane mirrors in degrees. Therefore, when
for θ=60, N=(36060)−1=5for θ=120,N=(360120)−1=2for θ=90, N=(36090)−1=3for θ=180,N=(360180)−1=1