Definition
Rotation
A rotation turns a shape around a fixed point by a chosen angle and direction.
What it means
Imagine pinning the page at one point and turning the shape around that pin. Every corner swings around the same centre through the same angle, so the shape changes direction but not size or shape. The turn may be clockwise or anticlockwise.
Remember it
Pin one point; swing the whole shape around it without stretching it.
Example
Triangle ABC makes a quarter-turn clockwise about point O. A marked corner that began directly to the right of O finishes directly below O, while all three side lengths stay the same.
Watch for
Sliding a shape to a new place without turning it is a translation, not a rotation.
Common mix-up
The centre of rotation is the fixed point of the turn; it does not have to be inside the shape.
Exact meaning
In plane geometry, a rotation is a transformation that turns every point of a figure through the same angle about one fixed point, called the centre of rotation. It preserves lengths and angle measures.