# Double Reflection over Intersecting Lines

- Author:
- Katie Drach

- Topic:
- Reflection

Move the slider to change the angle of the intersecting lines.

1. Click on the first checkbox to reflect ΔABC in Line1. Click and drag Point D to move Line1. Move around the vertices of the pre-image ΔABC. Record any observations you make about the image from the reflection.
2. Click on the second checkbox to reflect ΔA'B'C' in Line2. Click and drag Point D to move Line1. Does moving Line 1 affect ΔA"B"C" like it affects ΔA'B'C'? Explain your answer and make a conjecture as to why you think this is.
3. Move the red slider to change the angle at which the two lines intersect.
a. On which object does this have an affect?
b. As you move the slider, what is the relationship between the pre-image ΔABC and the final image ΔA"B"C"?
4. Click on the third checkbox to show ∡AEA". What is the relationship between the angle of the intersecting lines and ∡AEA"?

**Bonus:**Explain why the relationship stated in Question 4 always holds true.