Unit 19 Section 1 : Enlargement
An enlargement increases or decreases the size of a shape by a multiplier known as the scale factor. The angles in
the shape will not be changed by the enlargement, but the lengths of the sides will all be multiplied by the scale factor.
Because the angles always stay the same, the final shape is always in the same proportion as the original.
If the scale factor is 3, then every side will be three times bigger. If the scale factor is ½ then the lengths will be halved.
Note that even though the scale factor of ½ causes the shape to become smaller, it is still called an enlargement.
You can even have a scale factor of 1, which produces a shape identical to the original!
Practice Questions
Work out the answer to each of these questions then click on the button marked
to see whether you are correct.
Practice Question 1
Look at the triangles in the diagram below:
Some of the shapes are enlargements of triangle A.
For each of the other shapes, decide if it is an enlargement of A, and find the scale factor if it is.
Shape B:
Shape C:
Shape D:
Shape E:
Shape F:
Practice Question 2
Ameer has started to draw an enlargement of the quadrilateral marked A on the diagram below.
Work out where the final point in the enlarged shape will go, and the scale factor of the enlargement.
Exercises
Work out the answers to the questions below and fill in the boxes. Click on the
button to find out whether you have answered correctly. If you are right
then will appear and you should move on to the next
question. If appears then your answer is wrong. Click
on to clear your original answer and have another go.
If you can't work out the right answer then click on
to see
the answer.
NOTE: In the next few questions you need to plot points and draw lines on grids.
To plot a point, just click on the grid with your left mouse button. To draw a line,
hold down the left mouse button at one end of the line and drag the pointer to the
other end of the line. When you let go of the button the line will appear.
If you make a mistake, press the delete key and the grid will be cleared.


Question 7
Draw an enlargement of the rectangle shown with a scale factor of 3.
The first point is drawn for you, so you just need to plot three more points and draw in the four sides of the rectangle.
You need to upgrade your Flash PlayerGo to http://www.adobe.com/go/getflashplayer.
Question 8
Draw an enlargement of the triangle shown with a scale factor of 1½.
The first point is drawn for you, so you just need to plot two more points and draw in the three sides of the triangle.
You need to upgrade your Flash Player Go to http://www.adobe.com/go/getflashplayer.
Question 9
Denise has started to draw an enlargement of the shape below.
Complete her enlargement by drawing in the missing points and lines.
You need to upgrade your Flash Player Go to http://www.adobe.com/go/getflashplayer.
Question 10
Kristian has started to draw an enlargement of the shape below.
Complete his enlargement by drawing in the missing points and lines.
You need to upgrade your Flash Player Go to http://www.adobe.com/go/getflashplayer.
You have now completed Unit 19 Section 1
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