Given a line with end points $(x_1,y_1)$ $(x_2,y_2)$ and a circle centered at $(x_1,y_1)$ how do I calculate the angle of the line (in degrees) as it relates to the circle? If that doesn't make sense then please see my basic example below.
For the below examples I'm assuming $(x_1,y_1)$ is $(0,0)$ and the circle has a radius of 1.
$(x_2,y_2)$ -- (in degrees)
$(2,0)$ -- 0
$(0,2)$ -- 90
$(-2,0)$ -- 180
$(0,-2)$ -- 270