diff --git a/geom/demos/sat.py b/geom/demos/sat.py
index 8e10187..95434b3 100644
--- a/geom/demos/sat.py
+++ b/geom/demos/sat.py
@@ -76,7 +76,7 @@ class SeparatingAxisTheorem:
 
         def add_if_not_exists(normal):
             for existing in normals:
-                if is_equal(*existing, *normal):
+                if is_colinear(*existing, *normal):
                     return
             normals.append(normal)
 
diff --git a/geom/math.py b/geom/math.py
index 3734360..14d3e5a 100644
--- a/geom/math.py
+++ b/geom/math.py
@@ -58,8 +58,7 @@ def vmax(x1, y1, x2, y2):
     return max(x1, x2), max(y1, y2)
 
 
-def is_equal(x1, y1, x2, y2):
-    """Returns true if two unit vectors are pointed in either the same or
-    opposite directions.
-    """
+def is_colinear(x1, y1, x2, y2):
+    """Returns whether two unit vectors are pointed in the same or
+    opposite directions."""
     return math.isclose(abs(dot(x1, y1, x2, y2)), 1, rel_tol=1e-05)