Proof:
1. In the figure, the point at the top of the head, the eyes and a point at the feet of a person are indicated by H, E and F respectively.
2. R and S are midpoints of HE and EF respectively.
3. The mirror PQ is at a height of NQ from the ground and is perpendicular to it. PQ is the minimum height of the mirror in order to obtain the full image of the person.
For this, RP and QS must be perpendicular to the mirror.
Minimum height of the mirror
PQ = RS
= RE + ES
\(=\cfrac{HE}{2}+\cfrac{EF}{2}=\cfrac{HF}{2}\)
= Half of the person’s height.
