Calculating Angles Between Line Segments (Python) With Math.atan2
Answer : The easiest and most logically way to get at this problem is using the dot-product. Try this code (I've commented practically everything): import math def dot(vA, vB): return vA[0]*vB[0]+vA[1]*vB[1] def ang(lineA, lineB): # Get nicer vector form vA = [(lineA[0][0]-lineA[1][0]), (lineA[0][1]-lineA[1][1])] vB = [(lineB[0][0]-lineB[1][0]), (lineB[0][1]-lineB[1][1])] # Get dot prod dot_prod = dot(vA, vB) # Get magnitudes magA = dot(vA, vA)**0.5 magB = dot(vB, vB)**0.5 # Get cosine value cos_ = dot_prod/magA/magB # Get angle in radians and then convert to degrees angle = math.acos(dot_prod/magB/magA) # Basically doing angle <- angle mod 360 ang_deg = math.degrees(angle)%360 if ang_deg-180>=0: # As in if statement return 360 - ang_deg else: return ang_deg Now try your variations of lineA and lineB and all should give the same answer. An alternative solution using the fo...