Each transformation needs specific information to describe it
Translation → a column vector. Reflection → the equation of the mirror line. Rotation → angle, direction and centre. Enlargement → scale factor and centre. Give ALL parts.
Negative and fractional scale factors
A scale factor between −1 and 1 makes the image smaller; a negative scale factor also turns the image through the centre to the opposite side (and inverts it).
Drawn from real examiner reports.
Giving more than one transformation when asked for a single one
When the question says "single transformation", naming a second transformation (or "enlargement and translation") loses the mark even if one part is right.
Omitting the centre of an enlargement
Stating the scale factor but not the centre of enlargement only earns part of the marks.
Struggling to reflect in a diagonal line
Reflecting in a line such as or is done less accurately than reflecting in a horizontal or vertical line.
Reflecting in y = x: swap the coordinates
Under a reflection in , the point . Under , . Checking one vertex with this rule catches diagonal-mirror errors.
| Transformation | You must state |
|---|---|
| Translation | a column vector |
| Reflection | the equation of the mirror line (e.g. , ) |
| Rotation | angle, direction (clockwise/anticlockwise) and centre |
| Enlargement | scale factor and centre |
If a question asks for a single transformation, give exactly one — naming a second one withholds the mark.
A question asks for a single transformation — why lose a mark by naming two?
The point has coordinates . is translated by the vector . Find the coordinates of the image .
