Enlarge a shape to a given scale factor

1
Enlargements
Sunday, 04 October 2009
Its used in computer graphics Its used in
graphic design work It is a common SAT and GCSE
question

• Enlarge a shape to a given scale factor
• Enlarge a shape given a scale factor and a centre
  of enlargement.

Why are we doing this?
Level 7
2
Enlarge this triangle by a scale factor of 3.
The position of the enlarged triangle can be any
where on the grid.
X 3
6
2
1
3
X 3
3
Enlarge this triangle by a scale factor of 3
using (2, 1) as the centre of enlargement.
Draw lines from the centre of enlargement through
the vertices (corners) of the shape.
Use the lines to find the corners of the enlarged
shape
1
2
4
What about if I need to find the centre of
enlargement? For example where is the centre of
enlargement for these two triangles?
Draw lines through the corresponding vertices.
The point where the lines intersect is the centre
of enlargement. In this case, the centre is at
(3, 2)