Key Terms & Prime Notation

  • Translation: A slide. Points move the same distance in the same direction.
  • Reflection: A flip over a line of symmetry.
  • Rotation: A turn around a fixed point (0,0).
  • Dilation: Enlarging or reducing the shape by a scale factor.
  • Prime Notation: When a shape is transformed, the original points (Pre-image) are labeled with letters like A, B, C. The new points (Image) get a "prime" mark like A', B', C' (read as "A prime").

Translation (Slide)

Rule: (x, y) → (x + a, y + b)

Reflection (Flip)

Over X-Axis: (x, y) → (x, -y)
Over Y-Axis: (x, y) → (-x, y)
Over y=x: (x, y) → (y, x)

Rotation (Turn about Origin)

90° CCW: (x, y) → (-y, x)
180°: (x, y) → (-x, -y)
270° CCW: (x, y) → (y, -x)

Dilation (Resize from Origin)

Rule: (x, y) → (kx, ky)

Knowledge Check

1. If pre-image point A is (3, 4), what is A' under the translation (x-2, y+1)?



2. Which rule represents a reflection over the y-axis?



3. If a triangle is dilated by k=2, the point B(2, -3) becomes B':