Question

two mirrors at an angle θ produce 5 images at a point. The number of images produced when θ is decreased to 30o

Answer 1

You can use a formula

360/θ−1 will be the number of images formed (θis the angle between 2 mirrors)

so lets call θ, x

hence

360/x−1=5
360/x = 6
x = 360/6
x = 60°

Now if angle is decreased by 30° then angle between mirror will become 60° - 30° = 30°

Now, the no. of image formed will be ;

= 360/30-1
= 12 - 1
= 11 images. ..... Answer

Hope this helps you....:)