Question

A concave mirror has a radius of curvature of 40.5 cm and is positioned at a distance such that the upright image of a person's face is 1.5 times the size of his face. How far is the mirror from the person's face?

Answer 1

$m=-\frac{v}{u}\to v=-1.5u$

$1/v+1/u=2/R\to -1/(1.5u)+1/u=2/R\to$

$u=0.5R/3=0.5\cdot40.5/3=6.75\ (cm)$ . Answer