Page 380 - Math Smart - 7

16.2.3 Rotation

Rotation is a turn around a centre point called the centre of rotation. In a
rotation, every part of the object is turned around a fixed centre point to a new
position in a different orientation.
When a shape is rotated, The image and the object are congruent.
all points in the shape The centre of rotation can be on the object or at a distance from the object.
rotate through the same
angle.

The distance from the
centre of rotation to a
point on the object is the centre of centre of
rotation -
rotation
same as the distance from
the centre of rotation to
the corresponding point
on the Image.

Investigate!

Aim: To find out the effects of rotation on coordinate points and shapes and to map out
the image.
You will need:
• graph paper, a compass or dividers or pin, glue and the drawn-and-cut-out shapes from
the activity below
Instructions:

Rotation A Rotation B
O Look at the L-shape below. O Look at the L-shape below.
Draw and cut out an identical L-shape Draw and cut out an identical L-shape
(3 units by 4 units) on a piece of graph {3 units by 4 units) on a piece of graph
paper. paper.

0

Q Place the L-shape as shown on another piece Q Place the L-shape as shown on another piece
of graph paper. Trace and shade it. of graph paper. Trace and shade it.

UNIT 16 I Transformation