A beam of natural light is incident on the surface of a piece of glass of index 1.54 at an angle of incidence of 60 degrees. What fraction of the incident light is reflected

see the picture for the vector

the magnitude of the vector by pythagorean theorem

r = √( (-10)^2 + (3)^2 ) = √109

magnitude = √109 units

the direction angle between vector and x-axis is

tan^(-1)(3/10) = 16.699

so the direction is approximately 16.7 degrees north of west

find the sum of the two horizontal vectors and the sum of the two vertical vectors

isoceles right angled triangle