The Lesson
A rotation turns a shape.
A rotation is a turn of a shape about a point (called the centre of rotation).
A translation is a type of
transformation.
A Real Example of a Rotation
It is easier to understand rotation with an example.
The diagram below shows a rotation of a shape. The shape before the rotation (called the
object) is in light blue. The shape after the rotation (called the
image) is in dark blue:
In this example, the shape has rotated around a centre of rotation (shown as a
red cross) at the
origin.
Properties of a Rotation
-
All points move in a circle around the centre of rotation.
-
Each point in the image is the same distance from the centre of rotation as the object.
-
The image is the same size as the object.
Rotated Shapes Are Congruent Shapes
If a shape can be transformed to another using only rotation, then the two shapes are
congruent.
Congruent shapes have the same size, line lengths, angles and areas.
They are the same shape and size, just in a different position.
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