'Returns orientation of the sheet in radians'

def __getOrientation(self, markers):

    (x1, y1) = markers[0]
    (x2, y2) = markers[2]
    try:
        slope = (((x2 - x1) * 1.0) / ((y2 - y1) * 1.0))
    except ZeroDivisionError:
        slope = 999999999999999999999999999L
    return ((math.atan(slope) * (180.0 / math.pi)) * (-1))
