A translation occurs when a shape is moved from one place to another.
It is equivalent of picking up the shape and putting it down somewhere else.
Vectors are used to describe translations.
A reflection is like placing a mirror on the page. When describing a
reflection, you need to state the line which the shape has been reflected
in.
When describing a rotation, the centre and angle of rotation are
given. If you wish to use tracing paper to help with rotations: draw the shape
you wish to rotate onto the tracing paper and put this over shape. Push the end
of your pencil down onto the tracing paper, where the centre of rotation is and
turn the tracing paper through the appropriate angle. The resultant position of
the shape on the tracing paper is where the shape is rotated to.
Enlargements
Enlargements have a centre of enlargement and a scale factor. 1) Draw a
line from the centre of enlargement to each vertex ('corner') of the shape you
wish to enlarge. Measure the lengths of each of these lines. 2) If the scale
factor is 2, draw a line from the centre of enlargement, through each vertex,
which is twice as long as the length you measured. If the scale factor is 3,
draw lines which are three times as long. If the scale factor is 1/2, draw lines
which are 1/2 as long, etc.
Example
The centre of enlargement is
marked. Enlarge the triangle by a scale factor of 2.
Copyright © Matthew Pinkney 2003
