Short-Question

# What is the transformation rule for reflection?

## What is the transformation rule for reflection?

Coordinate plane rules: From the origin dilated by a factor of “c”: (x, y) → (cx, cy) From non-origin by factor of “c”: count slope from point to projection point, multiply by “c,” count from projection point. symmetry back onto itself. ✓ Rotations of 180o are equivalent to a reflection through the origin.

How do you know when a transformation is a reflection?

When you reflect a point across the x-axis, the x-coordinate remains the same, but the y-coordinate is transformed into its opposite (its sign is changed). If you forget the rules for reflections when graphing, simply fold your paper along the x-axis (the line of reflection) to see where the new figure will be located.

Which transformation must have occurred in order to map triangle RST?

Which transformation must have occurred in order to map triangle RST? A reflection will change the direction the vertices trace around the figure. A rotation preserves the change. Triangle RST is translated 2 units left and then reflected over the y-axis.

### Which axis is utilized to reflect the pre-image to produce the image?

To reflect a figure over a line, the points are the same distance from the line of reflection. Each point from the preimage is the same distance from the y-axis as its matching point in the image. Notice when we reflect over the y-axis, so the x-values are changing their sign.

Does a reflection change the direction the vertices trace around the figure?

Accurate. A reflection will change the direction the vertices trace around the figure. A rotation preserves the change. Alexi transformed figure L such that its image is figure K after a 90 degree counterclockwise rotation about the origin and a reflection over the y-axis.

Which transformation that could not transform the picture of the fork on the left to the one on the right?

Yes; all of the points have moved the same distance in the same direction. No; not all of the points have moved the same distance. Which transformation that could NOT transform the picture of the fork on the left to the one on the right? Rotation about point A by 180°.