diff -r b42788f5d0a9 -r eb74680a5e43 geometry.py
--- a/geometry.py	Tue Jan 16 17:29:40 2018 +0200
+++ b/geometry.py	Fri Jan 19 13:41:23 2018 +0200
@@ -188,15 +188,18 @@
         for v1, v2 in pairs(self.vertices):
             yield LineSegment(v1, v2)
     @property
-    def smallest_angle(self):
-        from math import acos, inf
-        min_angle = inf
+    def angles(self):
+        from math import acos
         for v1, v2, v3 in pairs(self.vertices, count = 3):
             vec1 = (position_vector(v3) - position_vector(v2)).normalized()
             vec2 = (position_vector(v1) - position_vector(v2)).normalized()
             cosine = dot_product(vec1, vec2) / vec1.length() / vec2.length()
-            min_angle = min(min_angle, angle_magnitude_key(acos(cosine)))
-        return min_angle
+            yield acos(cosine)
+    @property
+    def smallest_angle(self):
+        return min(
+            angle_magnitude_key(angle)
+            for angle in self.angles)
     @property
     def hairline_ratio(self):
         lengths = [line.length for line in self.perimeter_lines]