Which transformation changes the size of a shape?

enlargement. The others keep the shape exactly the same size.

What do you need to describe a reflection?

the mirror line. For example, the line x = 1.

The point (2, 3) is translated 4 right and 1 down. Where does it go?

(6, 2). Add 4 to x and subtract 1 from y.

A shape is enlarged with scale factor ½. What happens?

Its lengths are halved. A fractional scale factor makes it smaller.

The point (4, 1) is reflected in the y-axis. Where does it go?

(−4, 1). The x-coordinate changes sign.

Transformations · Cambridge IGCSE Mathematics (9

In plain words

A transformation moves or changes a shape. There are four kinds: flip it, turn it, slide it or resize it. To describe one fully you have to give every detail, and each detail is worth a mark.

Three things to know

Reflection: give the mirror line (such as x = 2, or y = x). Rotation: give the centre, the angle and the direction.
Translation: give the vector, such as 3 right and 2 down. Enlargement: give the centre and the scale factor.
A scale factor between 0 and 1 makes the shape smaller. A negative scale factor puts the image on the other side of the centre, upside down.

Worked example

Triangle A is enlarged to give triangle B. A side of 2 cm on A becomes 6 cm on B. What is the scale factor?

Scale factor = new length ÷ old length.
= 6 ÷ 2.
= 3.

Tips and tricks

"Describe fully" means name the transformation and give all its details: a rotation needs three things.
Use tracing paper for rotations, and count squares for translations.

5 questions, about 2 minutes.

It lands in your notebook with its questions as flashcards.

Transformations: 5 questions and answers

These are the quiz’s questions. Do the quiz first, then come back here for the ones that got you.

Which transformation changes the size of a shape?
- reflection
- rotation
- translation
- enlargement (the answer)
The others keep the shape exactly the same size.
What do you need to describe a reflection?
- a centre
- the mirror line (the answer)
- a vector
- an angle
For example, the line x = 1.
The point (2, 3) is translated 4 right and 1 down. Where does it go?
- (6, 4)
- (6, 2) (the answer)
- (−2, 4)
- (2, 7)
Add 4 to x and subtract 1 from y.
A shape is enlarged with scale factor ½. What happens?
- It doubles in size.
- Its lengths are halved. (the answer)
- It is reflected.
- Nothing.
A fractional scale factor makes it smaller.
The point (4, 1) is reflected in the y-axis. Where does it go?
- (4, −1)
- (−4, 1) (the answer)
- (1, 4)
- (−4, −1)
The x-coordinate changes sign.

5 questions

Tap an answer and you’ll see straight away whether it’s right, and why.

Worksheet

3 questions, 8 marks. Write your answers on paper, then check them.

Transformations

Cambridge IGCSE Mathematics (9–1) 0980 · 8 marks · papermunch.org

Name ______________________________ Date ______________

Describe fully the single transformation that maps a shape on to its image when every point moves 4 to the right and 3 down.[3]
Show answerHide answer
A translation by the vector (4, −3).
I got this one
The point (3, 5) is reflected in the x-axis. Write down the coordinates of its image.[2]
Show answerHide answer
(3, −5).
I got this one
State the three things needed to describe a rotation fully.[3]
Show answerHide answer
The centre of rotation, the angle, and the direction (clockwise or anticlockwise).
I got this one

Answers: Transformations

1. A translation by the vector (4, −3).
2. (3, −5).
3. The centre of rotation, the angle, and the direction (clockwise or anticlockwise).