Withe light becomes a spectrum of seven colored lights after passing through a prism

After passing through a prism, white light is spread out into it's spectrum, which includes all of the thousands of colors perceptible to the human eye. In the third grade, we learn seven names for colors that roughly span the visible range. But the truth is that there are hundreds of other colors between each pair of those names.

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