Question

A room is 3 m high and 5 m long. A man is lying down in front of one of the walls his eyes at a point 1m from the wall. A mirror is to be installed on the closer wall. The minimum height of the mirror from the ground so that complete image of the other wall is seen from that points is

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

Answer 1

The correct option is D 0.5 m

$\begin{array}{c}Fromthesmallertriangleabc\\ \tan \theta =\frac{h}{1}\\ fromthebiggertriangleCDE\\ \tan \theta =\frac{3h}{5}\\ Hence,\\ h=\frac{3-h}{5}\\ 6h=3\\ h=\frac{1}{2}=0.5m\\ Hence,theoptionDisthecorrectanswer.\end{array}$