The incident ray, reflected ray, and the outward drawn normal are denoted by the unit vectors \(\vec{a},\vec{b}\) and \(\vec{c}\) respectively, Then choose the correct relation for these vectors.
1. \( \vec{b}=\vec{a}+2 \vec{c} \)
2. \( \vec{b}=2 \vec{a}+\vec{c} \)
3. \( \vec{b}=\vec{a}-2(\vec{a} \cdot \vec{c}) \vec{c} \)
4. \( \vec{b}=\vec{a}-\vec{c} \)

A point source of light \(S\), placed at a distance \(60\) cm in front of the centre of a plane mirror of width \(50\) cm, hangs vertically on a wall. A man walks in front of the mirror along a line parallel to the mirror at a distance \(1.2\) m from it (see in the figure). The distance between the extreme points where he can see the image of the light source in the mirror is:

 
1. \(150\) cm
2. \(300\) cm
3. \(450\) cm
4. \(600\) cm