Question: A mirror is placed on the ground facing upwards. A man sees the top of a tower in the mirror which is at a distance of 100 m from the mirror. The man is 0.5 m away from the mirror, and his height is 1.5 m.
Solution: 
Given that,
Distance from the mirror to the tower = 100 m
Distance from the man to the mirror = 0.5 m
Height of the man = 1.5 m
Height of the tower, H = ?
Now,
⇒ Height of the man/Distance from man to mirror = Height of the tower/Distance from tower to mirror
⇒ 1.5/0.5 = H/100
⇒ 3 = H/100
⇒ H = 100 × 3 = 300 m