Question

calculate the nos. of images seen when two plane mirrors are placed inclined at an angle of 90 degree to each other.

Answer 1

there is a formula based on this type of questions:- N=(360/Θ)-1
where N is the number of images and Θ is he given angle
N= (360/90)-1
   =4-1=3
3 images will be frmed.

Answer 2

no. of images= (360/90)-1
=4-1
=3
So, it will form 3 images.