A transformation moves or changes a shape. A translation slides it. It is described by a vector such as (3, −2): 3 right and 2 down. A reflection flips it in a mirror line. A rotation turns it about a center by an angle.
Translations, reflections and rotations keep the shape the same size: the image is congruent. An enlargement changes the size by a scale factor, so the image is similar. Moving the point (−3, 1) by the vector (−1, −4) gives (−4, −3).
Worked example
The point (2, 5) is translated by the vector (4, −3). Find its image.
- Add the x parts: 2 + 4 = 6.
- Add the y parts: 5 + (−3) = 2.
Answer:(6, 2)
Key words
- translation
- a slide
- reflection
- a flip in a mirror line
- rotation
- a turn about a point
- congruent
- the same shape and size
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Common Core-referenced: 8.G.A.3