Laws of Refraction Using Huygens' Principle

Q. The wavefront of a light beam is given by the equation $x+2y+3x=c$ (where $c$ is arbitrary constant), then the angle made by the direction of light with the $y-$axis is

1. ${\sin }^{-1}\left(\frac{2}{\sqrt{14}}\right)$
2. ${\cos }^{-1}\left(\frac{2}{\sqrt{14}}\right)$
3. ${\sin }^{-1}\left(\frac{3}{\sqrt{14}}\right)$
4. ${\cos }^{-1}\left(\frac{1}{\sqrt{14}}\right)$

Q. A plane wavefront is incident on a convex mirror. After reflection, we will obtain

1. a cylindrical wavefront
2. a diverging wavefront
3. a plane wavefront
4. a converging wavefront