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Edexcel IGCSE Maths 復(fù)習(xí)筆記 5.2.1 Transformations - Rotation

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Edexcel IGCSE Maths 復(fù)習(xí)筆記 5.2.1 Transformations - Rotation

What are transformations in maths?

There are 4 transformations in GCSE Maths –?rotation, reflection, translation and enlargement
All 4 change a shape in some way, useful in things like computer graphics.
There is some language and notation often used in this topic – the original shape is called the?object?and the transformed shape is called the?image
Vertices on the object are labelled A, B, C, etc.And on the image they will be A’, B’, C’ etc.If there is a second transformation then they will become A”, B”, C” etc.

Rotation – what do I need to know?

You need to be able to perform a rotation (on a coordinate grid) as well as spotting and describing a rotation when presented with one
Rotation has 3 features:

1. Angle of rotation – how far we are going to rotate the shape by

2. Direction – clockwise or anti-clockwise

ClockwiseAnticlockwise

In the special case of 180° you will not need a direction

3. Centre of rotation – this is the point about which our rotation happens

It does NOT have to be a point that is on the shape nor in the middle of the shape; it can be anywhere

Exam Tip

Use tracing paper – it should be available although you will probably have to ask one of the invigilators for it. If you don’t want to do that during the exam, ask at the start – okay so a question may not turn up but if it does at least you’ve got it.Most angles are “nice” – 90°, 180°, etc. Draw an arrow facing “up” on your tracing paper. Then as you rotate it, it’ll be really easy to see when you’ve turned 90° (arrow will be facing left or right), 180° (arrow facing down) and so on.