Question

Question #327ab

Answer 1

I found: `90cm` and probably his sister will not be able to see her shoes...I think!

Explanation:

I considered the law of reflection (angle of incidence equal to angle of reflection) and some geometry to get:

The distances are:
`a` from top of the head to eyes;
`b` from eyes to shoes.

....I didn't use the distance from the mirror....!