The shortest height of a vertical mirror required to see the entire image of a man, will be

Options

A. one -third the man's height
B. half the man's height
C. two-third the man's height
D. data insufficient

Answer

B

Explanation

(b) Let `MN=` height of a man
`E=` position if eye

As `DeltaNGQ` and `DeltaQGE` are similar,
`DeltaESP` and `DeltaPSM` are congruent.
`MP=PE=EQ=QN`
Now, `SG=PQ=PE+EQ`
`SG=(ME)/2+(EN)/2`
`SG=1/2MN`