3.3Reflections
Quick Answer
A reflection flips a figure over a line of reflection. Key rules: over x-axis: (x,y)→(x,−y); over y-axis: (x,y)→(−x,y); over y=x: (x,y)→(y,x); over y=−x: (x,y)→(−y,−x). Each image point is the same distance from the line as its pre-image.
Essential Question
How does a reflection transform coordinates, and what is the relationship between a point and its image with respect to the line of reflection?
Learning Goals
- 1Reflect figures over the x-axis, y-axis, y=x, and y=−x.
- 2Apply coordinate rules for reflections.
- 3Find the line of reflection given a pre-image and image.
- 4Verify that a reflection is a rigid motion.
Key Vocabulary
Reflection
A transformation that flips a figure over a line of reflection.
Line of reflection
The line over which a figure is reflected; each point and its image are equidistant from this line.
Full lesson content coming soon
Worked examples, guided practice problems, a workbook, quiz, and downloadable PDF resources will be added to this lesson in Phase 2. The learning goals and vocabulary above reflect the complete lesson scope.