6.4. Rotation

Definition: A rotation 𝑅 about an angle 𝜃 is a transformation of the plane onto itself which carries every point 𝐴 of the plane into the point P′ of the plane such that 𝑂𝑃=𝑂𝑃′ and 𝑚(∠𝑃𝑂𝑃′ )=𝜃. 𝑂 is called the centre of rotation and 𝜃 is called the angle of rotation.