Reflecting a point about a line
Construction
1) Create a point A.
2) Reflect point A about the x-axis
3) Label the reflection point A' (right click on the point and choose 'Rename').
Next...
4) Create a point B at (1,2) and change the color of the point to red under the style bar
5) Reflect point B about the line y=x and change the color of the point to red under the style bar.
6) Label the reflection point B' (right click on the point and choose 'Rename').
Finally...
7) Create a point C on the line y=x and change the points color.
Reflection about lines
Question 1
What is the coordinate for A'?
Question 2
What is the coordinate for B'?
Question 3
What do you notice about the distance from point B to the line of reflection and the distance from point B' to the line of reflection? Do you think this observation holds true for all reflections of a point?
Question 4
What happens if you reflect point C about the line it is on?
8th grade Geometry:Understand congruence and similarity using physical models,
transparencies, or geometry software.CCSS.MATH.CONTENT.8.G.A.1
Verify experimentally the properties of rotations, reflections, and
translations