1. Licensing information
Users should treat this material as a working draft. This material can be used in its current form, customized, redistributed and/or printed or displayed by the user.
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This material is licensed under the Creative Commons Attribution license: (
Author: Kevin Hall
Wording for the legal statement above is adapted from the legal statement for Trigonometry, published in 2009 by The CK-12 Foundation:

2. Comparing Corresponding Angles With Tracing Paper1 1 2
Where should go to be corresponding to ?
Trace on tracing paper.

3. Comparing Corresponding Angles With Tracing Paper1 1 2
The angles match up perfectly!
They’re congruent.
Slide your trace of onto and compare them.

4. Comparing Corresponding Angles With Tracing Paper1 1 2
The angles match up perfectly!
They’re congruent.
Tape your tracing paper down on

5. How it looks when they’re NOT congruent…

6. Is ? 2 1 1

7. Is ? 1 2 1

8. We can’t compare them yet.
Is ? 1 2 1
Not lined up!!!
We can’t compare them yet.

9. Is ? 1 2 1

10. Is ? 1 2 1

11. Is ? 1 2 1

12. Is ? 1 2 1

13. Is ? 1 2 1

14. Is ? 1 2 1
Still not lined up!!!

15. Now it’s lined up correctly
Is ?
Now it’s lined up correctly 1 2 1

16. Angle 1 and Angle 2 do not match up. They are not congruent.
Is ? 1 2 1
Angle 1 and Angle 2 do not match up.
They are not congruent.