Question

A room is 3m high and 5m long. A man is standing in front of one of the walls 1 m from the wall. A mirror is to be installed on the wall. Find the height (minimum) of the mirror so that complete image of the wall behind him is seen.

• A. 1.5 m
• B. 1 m
• C. 2 m
• D. 0.5 m

Answer 1

The correct option is D 0.5 m

From the figure, the triangles, $\Delta ABM$ and $\Delta KLM$ are similar.

$⟹\frac{KL}{AB}=\frac{KM}{MB}$

$⟹KL=\frac{KM\times AB}{MB}$

$⟹KL=\frac{1\times 3}{6}=\frac{1}{2}m=0.5m$