diff --git a/govector_test.go b/govector_test.go
index ddd2f26..e0a458d 100644
--- a/govector_test.go
+++ b/govector_test.go
@@ -138,8 +138,8 @@ func TestAngle(t *testing.T) {
 
 	a := Angle(v2, v1)
 
-	fmt.Printf("%v %v %f\n", v1, v2, a*rad2deg)
-	if math.Abs(a-math.Pi/2) > epsilon {
+	fmt.Printf("%v %v %f\n", v1, v2, a*Rad2deg)
+	if math.Abs(a)-math.Pi/2 > epsilon {
 		t.Errorf("Angle Error")
 	}
 
@@ -148,10 +148,28 @@ func TestAngle(t *testing.T) {
 
 	a = Angle(v1, v2)
 
-	fmt.Printf("%v %v %f\n", v1, v2, a*rad2deg)
+	fmt.Printf("%v %v %f\n", v1, v2, a*Rad2deg)
 
-	if math.Abs(a-math.Pi/4) > epsilon {
+	if math.Abs(a)-math.Pi/4 > epsilon {
 		t.Errorf("Angle Error")
 	}
 
 }
+
+func TestRotate(t *testing.T) {
+	v1 := Vector2d{10, 0}
+	v2 := v1.Rotate(math.Pi / 2)
+
+	fmt.Printf("%v %v\n", v1, v2)
+	if v2.X > epsilon || v2.Y-10 > epsilon {
+		t.Errorf("Rotate Error")
+	}
+
+	v1 = Vector2d{1, 0}
+	v2 = v1.Rotate(-30 * Deg2rad)
+
+	fmt.Printf("%v %v\n", v1, v2)
+	if v2.X-0.866025403784438 > epsilon || v2.Y+0.5 > epsilon {
+		t.Errorf("Rotate Error")
+	}
+}
diff --git a/vectorpoint.go b/vectorpoint.go
index 4f2222e..e5e204f 100644
--- a/vectorpoint.go
+++ b/vectorpoint.go
@@ -22,7 +22,8 @@ type Point2d struct {
 }
 
 const epsilon = 1e-7
-const rad2deg = 180 / math.Pi
+const Rad2deg = 180 / math.Pi
+const Deg2rad = math.Pi / 180
 
 func (p1 Point2d) Sub(p2 Point2d) Vector2d {
 	return Vector2d{p1.X - p2.X, p1.Y - p2.Y}
@@ -52,6 +53,12 @@ func (v1 Vector2d) Dot(v2 Vector2d) float64 {
 	return (v1.X * v2.X) + (v1.Y * v2.Y)
 }
 
+func (v1 Vector2d) Rotate(a float64) Vector2d {
+	x := v1.X*math.Cos(a) - v1.Y*math.Sin(a)
+	y := v1.X*math.Sin(a) + v1.Y*math.Cos(a)
+	return Vector2d{x, y}
+}
+
 func Intersection(p1, p2 Point2d, v1, v2 Vector2d) (bool, Point2d) {
 	t := p2.Sub(p1).Cross(v2) / v1.Cross(v2)
 	s := p2.Sub(p1).Cross(v1) / v1.Cross(v2)
@@ -84,5 +91,11 @@ func Distance(p1, p2 Point2d) float64 {
 
 func Angle(v1, v2 Vector2d) float64 {
 	x := (v1.Dot(v2) / (v1.Mag() * v2.Mag()))
-	return math.Acos(x)
+	angle := math.Acos(x)
+	// Determine the sign to see what direction
+	// the angle should go in
+	if v1.Y*v2.X > v1.X*v2.Y {
+		angle = angle * -1.0
+	}
+	return angle
 }