Look in a mirror - your reflection is the same distance BEHIND the mirror as you are in front. Mathematical reflections work exactly the same way. Each point moves to a position the same distance on the OTHER side of the mirror line, moving perpendicular to it.
This introduction covers Mirror Maths 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 1 of 6 in this topic. Use this introduction to connect the idea to the wider topic before moving on to questions and flashcards.
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)