Compute an angle in 2D space
get_2d_angle(x1, y1, x2, y2, x3, y3)
x-coordinate of first point
y-coordinate of first point
x-coordinate of second point (vertex)
y-coordinate of second point (vertex)
x-coordinate of third point
y-coordinate of third point
A numeric vector that provides the angular measurement in degrees.
Everything supplied to arguments must be singular numeric values. The second point (x2, y2) is treated as the vertex, and the angle between the three points in 2D space is computed.
Vikram B. Baliga
get_2d_angle( 0, 1, 0, 0, 1, 0) #>  90