This exam tips covers Exam Tips within Transformations: Reflections for GCSE Mathematics. Revise Transformations: Reflections in Geometry & Measures for GCSE Mathematics with 13 exam-style questions and 5 flashcards. This topic appears less often, but it can still be a useful differentiator on mixed-topic papers. It is section 5 of 6 in this topic. Treat this as a marking guide for what examiners are looking for, not just a fact list.
Exam Tips
X Just saying "reflection"
Always state the mirror line equation
e.g., "Reflection in the line y = x"
X Confusing x = a and y = a
x = a is VERTICAL, y = a is HORIZONTAL
Think: x-axis is horizontal but x = number is vertical!
Practice questions for Transformations: Reflections
A point P has coordinates (3, 5). It is reflected in the x-axis. What are the coordinates of its image P'?
Fully describe the single transformation that maps shape A onto shape B. Shape A has vertices at (1, 1), (3, 1), (3, 4) and shape B has vertices at (−1, 1), (−3, 1), (−3, 4).
Quick recall flashcards
Reflecting in y = x
Swap x and y coordinates. Example: (3,4) → (4,3)
Reflecting in y = -x
Swap coordinates AND change both signs. (x,y) → (-y,-x). Example: (3,4) → (-4,-3)