Cumulative Practice
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Reflected points are the same distance from but on opposite sides of the line of reflection before and after the reflection takes place.
C
Consider the given triangle.
We want to reflect this figure over the x-axis. To do so, we need to plot each vertex of the image X'Y'Z' the same distance from the line of reflection as its corresponding vertex on the preimage XYZ. Because our line of reflection is the x-axis, this will change the sign of the y-coordinates of the points, but the x-coordinates will remain unchanged.
| Preimage XYZ | Image X'Y'Z' | ||
|---|---|---|---|
| Vertex | Distance From the x-axis | Vertex | Distance From the x-axis |
| X(- 4,1) | 1 unit above the x-axis | X'(- 4,- 1) | 1 unit below the x-axis |
| Y(- 2,3) | 3 units above the x-axis | Y'(- 2,- 3) | 3 units below the x-axis |
| Z(2,1) | 1 unit above the x-axis | Z'(2,- 1) | 1 unit below the x-axis |
