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### Course: High school geometry>Unit 1

Lesson 5: Reflections

# Reflecting shapes: diagonal line of reflection

Sal is given two line segments on the coordinate plane and the definition of a reflection, and he draws the image of the segments under that reflection.

## Want to join the conversation?

• How can I do this without a scratch pad? The actual activity does not allow drawing and even Sal had to go to another page to draw. I am struggling on questions that you can't just eyeball like -3x and stuff. Please help, thanks.
• Actually, I was able to eyeball the stuff on the exercises. For diagonal lines, just count diagonally how many points it takes to get to the line of reflection, and count that many points on the other side.
• not going to lie this stuff not making sense let me mind u again a senior in high school
• That's school for ya LOL.
• In the exercise for this, it just gave me a line segment with no way to add vertices. How do I do the excercise?
• In the following exercise, you need to click the graph to add vertices. For the exercise after that, click and drag the points to their proper positions depicting the line of reflection.
• How would you reflect a shape if it was on both sides of the line of reflection?
• Just invert the coordinate values of every point; every positive changes to a negative and vice versa.
For example, -X becomes X, and -Y becomes Y.
• My moms 36 and its breaking HER head, much less mine.
• This doesn't help me because I'm trying to reflect a triangle over a diagonal line, not a line segment.
• Can't I just count the diagonal squares to find the correct point on the reflection? I guess it would depend on what the slope is though.
• So you are correct in that it depends on the slope. the line that you would draw would be perpendicular to the line of reflection, so as long as the line of reflection has either a positive or negative 1 slope, counting diagonals works well.
• So that little triangle thing means change? Like, change in the number or variable? Is there a video on that?