This needs 2 pieces of information:
1. Scale factor.
2. Centre of Enlargement.
You draw lines from the centre of enlargement through each corner of the shape. The new enlarged shape will have its corresponding corners on these lines. The scale factor tells you where.
To draw the new shape you multiply the distances of each corner from the centre of enlargement by the scale factor and that is the distance of your new shape from the centre of enlargement.
The example opposite shows an enlargement of triangle ABC with scale factor 2 and centre of enlargement (1,1).
Note: A fractional scale factor leads to a reduction in size. A negative scale factor means you go the opposite direction to draw your new shape.
Reproduce these shapes one by one on grid paper, and enlarge each one from Centre of Enlargement A by scale factor below.
Find the Scale Factor and the Centre of Enlargement for each pair of similar shapes.
Trace the image of this shape with an Enlargement of centre Q and by Scale Factor -2.
Rotate the first small shape about point Q, anticlockwise, by an angle of 90°.