Show that the minimum size of a plane mirror required to see the full image of an observer is half the size of that observer.

Explanation

See the following figure. It is self explanatory if you consider lengths 'x' and 'y' as shown in figure.

Aliter : `Delta E M_(1), M_(2)` and `DeltaE` H' F' are similar
`:. (M_(1)M_(2))/(H'F')=z/(2z)`
or `M_(1)M_(2)=H'F'//2=HF//2`