The light-ray first strike the surface at angle of 5 degrees.
Explanation:
It is given that,
If a light Ray is reflected off the shiny surface at 170 degrees. We have to determine the light- ray first strike the surface. It is based on the laws of reflection which states that the angle of incidence is equal to the angle of reflection.
Here, the angle between the reflected ray and the surface is 170 degrees. So, it is clear that the angle between the incident ray and the surface is 5 degrees.