We can see that it is an enlargement but note that the question asks for the transformation from C to A.
Triangle C is clearly smaller than Triangle A, so it is an enlargement by a fractional (not negative) scale factor.

Draw three construction lines from vertices on Triangle A to corresponding vertices on Triangle C, as in the diagram below. Where the three lines intersect is the centre of enlargement. We can see this is the point (-4, 0).

cie-igcse-2018-may-jun-1-p4-q4aii

The scale factor of enlargement is $\frac{distance from centre to image (C)}{distance from centre to object (A)}$ . We can measure these distances along the $x$ - and $y$ - axes. For example, from the top left vertices, (0, 2.5) on C and (4, 5) on A;

$\frac{x distance from (0, 2.5) to (-4, 0)}{x distance from (4, 5) to (- 4, 0)} = \frac{- 4}{- 8} = \frac{1}{2} and \frac{y distance from (0, 2.5) to (-4, 0)}{y distance from (4, 5) to (- 4, 0)} = \frac{- 2.5}{- 5} = \frac{1}{2}$

"Enlargement about (-4, 0), scale factor $\frac{1}{2}$ "

"enlargement" [1]

correct centre [1]

correct scale factor [1]

Don't be tempted to describe the scale factor as a negative number! Negative scale factors involve a rotation by 180°

Transformations (CIE IGCSE Maths: Extended)

Exam Questions