Answer:
distance of image = 12 cm
Step-by-step explanation:
For plane mirror the perpendicular distance of object from the mirror must be same as that of perpendicular distance of image from the mirror
As we know here that object is 3 cm high
But the distance of object from mirror is 12 cm
So here the image will be virtual and it will form at 12 cm distance behind the mirror.
So here image will form behind the mirror at same distance that is the distance of object from the mirror.