diff -r c71a7d863c2e -r b8d72909d593 geometry.py
--- a/geometry.py	Mon Jun 24 11:48:52 2019 +0300
+++ b/geometry.py	Mon Jun 24 17:31:47 2019 +0300
@@ -325,6 +325,8 @@
             x * scalar
             for x in self.values
         ])
+    def is_mirrored(self):
+        return self.determinant() < 0
 
 def complete_matrix(matrix, anchor):
     '''