Edexcel IGCSE Maths 复习笔记 5.5.1 Combined Transformations

Combined Transformations – what do I need to know?

• Combined transformations are more than one transformation, one performed after the after
• It is often the case that 2 transformations can be equivalent to 1 alternative transformation and you will be expected to spot those
• Here’s a reminder of the transformations:

1. Rotation

• Requires an angle, direction and centre of rotation
• It is usually easy to tell the angle from the orientation of the image
• Use some instinct and a bit of trial and error to find the centre of enlargement.

2. Reflection

• Mirror line – can be vertical (x = k), horizontal (y = k) or diagonal (y = mx + c)
• Points on the mirror line do not move
• Double reflections are possible if the mirror line passes through the object

4. Enlargement

• A scale factor and centre of enlargement are needed for an enlargement
• Enlargements can make shapes smaller if scale factor is fractional
• Area scale factor is the scale factor squared
• Negative scale factors mean the shape is enlarged on the other side of the centre of enlargement