Geometry & measures · Transformations
Chapter 1 · 4
The idea
Reflections & rotations
Reflecting in named mirror lines including y = x and y = −x, rotating about a given centre with a sense, and the exact wording needed to DESCRIBE a transformation for full marks.
A full journey — read it, play with it, work it, then earn real exam marks. Everything stays on the timeline below.
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Geometry & measures · Transformations
Reflections & rotations
Reflecting in named mirror lines including y = x and y = −x, rotating about a given centre with a sense, and the exact wording needed to DESCRIBE a transformation for full marks.
Why it works
Same shape, same size, new position
A transformation moves every point by the same rule. Reflections and rotations are congruent transformations: the image is the same shape and the same size as the object — only its position or orientation changes. That is the first thing an exam answer can say about them, and the reason tracing paper works at all.Reflection: across the mirror, same distance
If is 3 squares above the mirror line, is 3 squares below it, measured perpendicular to the line. So reflect one vertex at a time, then join up. In the two diagonal cases the coordinates swap:Keep reading — free
The rest of the explanation, plus 2 worked examples you step through move by move.
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