Problem

The wavefront of a light beam is given by the equation

x + 2y + 3z = c

, (where

c

is arbitrary constant) then the angle made by the direction of light with the

y

-axis is: (a)

\cos^{-1} \frac{1}{\sqrt{14}}

(b)

\cos^{-1} \frac{2}{\sqrt{14}}

(c)

\sin^{-1} \frac{1}{\sqrt{4}}

(d)

\sin^{-1} \frac{2}{\sqrt{4}}