Question

A ray of light travelling along the line x + y = 1 is inclined on the x axis and after refraction it enters the other side of the x axis by turning 15 degree away from the x axis. the equation of the line along which ythe refraction ray travels is

Answer 1

I am assuming you have an idea about the basic principles of refraction. Now have a look at the figure and it is pretty clear that the slope of the refracted line is

m = tan(180-60) = tan(120) = -sqrt of 3

and we have the point where the line x+y=1 meets x axis i.e (1,0), the refracted line will also pass through the same point.

So now we have the standard point slope form given as

(y-y_1) = m(x-x_1)

we have the line as

y = - sqrt of 3 (x-1)

y + sqrt of 3x = sqrt of 3 is the answer