diff --git a/src/matrix.rs b/src/matrix.rs
index 6cf355a..50fb8a2 100644
--- a/src/matrix.rs
+++ b/src/matrix.rs
@@ -103,12 +103,11 @@ impl<S: BaseFloat> Matrix2<S> {
     }
 
     #[inline]
-    pub fn from_angle(theta: Rad<S>) -> Matrix2<S> {
-        let cos_theta = Rad::cos(theta);
-        let sin_theta = Rad::sin(theta);
+    pub fn from_angle<A: Into<Rad<S>>>(theta: A) -> Matrix2<S> {
+        let (s, c) = Rad::sin_cos(theta.into());
 
-        Matrix2::new(cos_theta,  sin_theta,
-                     -sin_theta, cos_theta)
+        Matrix2::new(c,  s,
+                     -s, c)
     }
 }
 
@@ -140,27 +139,27 @@ impl<S: BaseFloat> Matrix3<S> {
     }
 
     /// Create a rotation matrix from a rotation around the `x` axis (pitch).
-    pub fn from_angle_x(theta: Rad<S>) -> Matrix3<S> {
+    pub fn from_angle_x<A: Into<Rad<S>>>(theta: A) -> Matrix3<S> {
         // http://en.wikipedia.org/wiki/Rotation_matrix#Basic_rotations
-        let (s, c) = Rad::sin_cos(theta);
+        let (s, c) = Rad::sin_cos(theta.into());
         Matrix3::new(S::one(), S::zero(), S::zero(),
                      S::zero(), c, s,
                      S::zero(), -s, c)
     }
 
     /// Create a rotation matrix from a rotation around the `y` axis (yaw).
-    pub fn from_angle_y(theta: Rad<S>) -> Matrix3<S> {
+    pub fn from_angle_y<A: Into<Rad<S>>>(theta: A) -> Matrix3<S> {
         // http://en.wikipedia.org/wiki/Rotation_matrix#Basic_rotations
-        let (s, c) = Rad::sin_cos(theta);
+        let (s, c) = Rad::sin_cos(theta.into());
         Matrix3::new(c, S::zero(), -s,
                      S::zero(), S::one(), S::zero(),
                      s, S::zero(), c)
     }
 
     /// Create a rotation matrix from a rotation around the `z` axis (roll).
-    pub fn from_angle_z(theta: Rad<S>) -> Matrix3<S> {
+    pub fn from_angle_z<A: Into<Rad<S>>>(theta: A) -> Matrix3<S> {
         // http://en.wikipedia.org/wiki/Rotation_matrix#Basic_rotations
-        let (s, c) = Rad::sin_cos(theta);
+        let (s, c) = Rad::sin_cos(theta.into());
         Matrix3::new( c, s, S::zero(),
                      -s, c, S::zero(),
                      S::zero(), S::zero(), S::one())
@@ -169,8 +168,8 @@ impl<S: BaseFloat> Matrix3<S> {
     /// Create a rotation matrix from an angle around an arbitrary axis.
     ///
     /// The specified axis **must be normalized**, or it represents an invalid rotation.
-    pub fn from_axis_angle(axis: Vector3<S>, angle: Rad<S>) -> Matrix3<S> {
-        let (s, c) = Rad::sin_cos(angle);
+    pub fn from_axis_angle<A: Into<Rad<S>>>(axis: Vector3<S>, angle: A) -> Matrix3<S> {
+        let (s, c) = Rad::sin_cos(angle.into());
         let _1subc = S::one() - c;
 
         Matrix3::new(_1subc * axis.x * axis.x + c,
@@ -244,9 +243,9 @@ impl<S: BaseFloat> Matrix4<S> {
     }
 
     /// Create a homogeneous transformation matrix from a rotation around the `x` axis (pitch).
-    pub fn from_angle_x(theta: Rad<S>) -> Matrix4<S> {
+    pub fn from_angle_x<A: Into<Rad<S>>>(theta: A) -> Matrix4<S> {
         // http://en.wikipedia.org/wiki/Rotation_matrix#Basic_rotations
-        let (s, c) = Rad::sin_cos(theta);
+        let (s, c) = Rad::sin_cos(theta.into());
         Matrix4::new(S::one(), S::zero(), S::zero(), S::zero(),
                      S::zero(), c, s, S::zero(),
                      S::zero(), -s, c, S::zero(),
@@ -254,9 +253,9 @@ impl<S: BaseFloat> Matrix4<S> {
     }
 
     /// Create a homogeneous transformation matrix from a rotation around the `y` axis (yaw).
-    pub fn from_angle_y(theta: Rad<S>) -> Matrix4<S> {
+    pub fn from_angle_y<A: Into<Rad<S>>>(theta: A) -> Matrix4<S> {
         // http://en.wikipedia.org/wiki/Rotation_matrix#Basic_rotations
-        let (s, c) = Rad::sin_cos(theta);
+        let (s, c) = Rad::sin_cos(theta.into());
         Matrix4::new(c, S::zero(), -s, S::zero(),
                      S::zero(), S::one(), S::zero(), S::zero(),
                      s, S::zero(), c, S::zero(),
@@ -264,9 +263,9 @@ impl<S: BaseFloat> Matrix4<S> {
     }
 
     /// Create a homogeneous transformation matrix from a rotation around the `z` axis (roll).
-    pub fn from_angle_z(theta: Rad<S>) -> Matrix4<S> {
+    pub fn from_angle_z<A: Into<Rad<S>>>(theta: A) -> Matrix4<S> {
         // http://en.wikipedia.org/wiki/Rotation_matrix#Basic_rotations
-        let (s, c) = Rad::sin_cos(theta);
+        let (s, c) = Rad::sin_cos(theta.into());
         Matrix4::new( c, s, S::zero(), S::zero(),
                      -s, c, S::zero(), S::zero(),
                      S::zero(), S::zero(), S::one(), S::zero(),
@@ -276,8 +275,8 @@ impl<S: BaseFloat> Matrix4<S> {
     /// Create a homogeneous transformation matrix from an angle around an arbitrary axis.
     ///
     /// The specified axis **must be normalized**, or it represents an invalid rotation.
-    pub fn from_axis_angle(axis: Vector3<S>, angle: Rad<S>) -> Matrix4<S> {
-        let (s, c) = Rad::sin_cos(angle);
+    pub fn from_axis_angle<A: Into<Rad<S>>>(axis: Vector3<S>, angle: A) -> Matrix4<S> {
+        let (s, c) = Rad::sin_cos(angle.into());
         let _1subc = S::one() - c;
 
         Matrix4::new(_1subc * axis.x * axis.x + c,
diff --git a/src/quaternion.rs b/src/quaternion.rs
index 3414eb6..bef4851 100644
--- a/src/quaternion.rs
+++ b/src/quaternion.rs
@@ -387,8 +387,8 @@ impl<S: BaseFloat> Rotation<Point3<S>> for Quaternion<S> {
 
 impl<S: BaseFloat> Rotation3<S> for Quaternion<S> {
     #[inline]
-    fn from_axis_angle(axis: Vector3<S>, angle: Rad<S>) -> Quaternion<S> {
-        let (s, c) = Rad::sin_cos(angle * cast(0.5f64).unwrap());
+    fn from_axis_angle<A: Into<Rad<S>>>(axis: Vector3<S>, angle: A) -> Quaternion<S> {
+        let (s, c) = Rad::sin_cos(angle.into() * cast(0.5f64).unwrap());
         Quaternion::from_sv(c, axis * s)
     }
 }
diff --git a/src/rotation.rs b/src/rotation.rs
index 0f93ad0..829e204 100644
--- a/src/rotation.rs
+++ b/src/rotation.rs
@@ -62,7 +62,7 @@ pub trait Rotation2<S: BaseFloat>: Rotation<Point2<S>>
                                  + Into<Basis2<S>> {
     /// Create a rotation by a given angle. Thus is a redundant case of both
     /// from_axis_angle() and from_euler() for 2D space.
-    fn from_angle(theta: Rad<S>) -> Self;
+    fn from_angle<A: Into<Rad<S>>>(theta: A) -> Self;
 }
 
 /// A three-dimensional rotation.
@@ -74,23 +74,23 @@ pub trait Rotation3<S: BaseFloat>: Rotation<Point3<S>>
     /// Create a rotation using an angle around a given axis.
     ///
     /// The specified axis **must be normalized**, or it represents an invalid rotation.
-    fn from_axis_angle(axis: Vector3<S>, angle: Rad<S>) -> Self;
+    fn from_axis_angle<A: Into<Rad<S>>>(axis: Vector3<S>, angle: A) -> Self;
 
     /// Create a rotation from an angle around the `x` axis (pitch).
     #[inline]
-    fn from_angle_x(theta: Rad<S>) -> Self {
+    fn from_angle_x<A: Into<Rad<S>>>(theta: A) -> Self {
         Rotation3::from_axis_angle(Vector3::unit_x(), theta)
     }
 
     /// Create a rotation from an angle around the `y` axis (yaw).
     #[inline]
-    fn from_angle_y(theta: Rad<S>) -> Self {
+    fn from_angle_y<A: Into<Rad<S>>>(theta: A) -> Self {
         Rotation3::from_axis_angle(Vector3::unit_y(), theta)
     }
 
     /// Create a rotation from an angle around the `z` axis (roll).
     #[inline]
-    fn from_angle_z(theta: Rad<S>) -> Self {
+    fn from_angle_z<A: Into<Rad<S>>>(theta: A) -> Self {
         Rotation3::from_axis_angle(Vector3::unit_z(), theta)
     }
 }
@@ -197,7 +197,7 @@ impl<S: BaseFloat> ApproxEq for Basis2<S> {
 }
 
 impl<S: BaseFloat> Rotation2<S> for Basis2<S> {
-    fn from_angle(theta: Rad<S>) -> Basis2<S> { Basis2 { mat: Matrix2::from_angle(theta) } }
+    fn from_angle<A: Into<Rad<S>>>(theta: A) -> Basis2<S> { Basis2 { mat: Matrix2::from_angle(theta) } }
 }
 
 impl<S: fmt::Debug> fmt::Debug for Basis2<S> {
@@ -285,19 +285,19 @@ impl<S: BaseFloat> ApproxEq for Basis3<S> {
 }
 
 impl<S: BaseFloat> Rotation3<S> for Basis3<S> {
-    fn from_axis_angle(axis: Vector3<S>, angle: Rad<S>) -> Basis3<S> {
+    fn from_axis_angle<A: Into<Rad<S>>>(axis: Vector3<S>, angle: A) -> Basis3<S> {
         Basis3 { mat: Matrix3::from_axis_angle(axis, angle) }
     }
 
-    fn from_angle_x(theta: Rad<S>) -> Basis3<S> {
+    fn from_angle_x<A: Into<Rad<S>>>(theta: A) -> Basis3<S> {
         Basis3 { mat: Matrix3::from_angle_x(theta) }
     }
 
-    fn from_angle_y(theta: Rad<S>) -> Basis3<S> {
+    fn from_angle_y<A: Into<Rad<S>>>(theta: A) -> Basis3<S> {
         Basis3 { mat: Matrix3::from_angle_y(theta) }
     }
 
-    fn from_angle_z(theta: Rad<S>) -> Basis3<S> {
+    fn from_angle_z<A: Into<Rad<S>>>(theta: A) -> Basis3<S> {
         Basis3 { mat: Matrix3::from_angle_z(theta) }
     }
 }