Two rays are incident on a spherical mirror of radius R = 5cm. parallel to its optical axis at a distance ${\text{h}}_{\text{1}}=0.5\text{mm}\text{and}{\text{h}}_{\text{2}}=3\text{cm}$ from the optic axis. Determine the distance $\Delta x$  (approximately) between the points at which these rays intersect the optical axis after being reflected at the mirror.