Question

a person holds a plane mirror 1.0m in the front of his eyes and is able to see a 15 m high object behind him.if the mirror is 20 cm high,and the object completely fills the mirror, how far the person is standing from the object

Answer 1

Let the distance of the person from the object be = D meters

Distance of image from mirror = D + 1  meters

The triangle made by image of object, at the eyes and triangle made by mirror at the eyes have the same angle of elevation.

Distance of the image from the eyes = D + 2 meters

Hence  15 / 0.20 = (D+2) / 1   

      Solving it  D = 73 meters