Problem 19 of 7
Prove the triangle angle-sum theorem using parallel lines for triangle STU.
Using a hint is okay. It just tells the trainer to give you a little more review.
Hidden until you reveal it.
use alternate interior/corresponding angles.
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Proof must use an auxiliary parallel line and corresponding or alternate interior angles.
Enter your answer
Your answer is equivalent to the expected form.
Walkthrough
Full solution stays hidden until you ask for it.
1. Draw a parallel line through one vertex.
2. Use alternate interior or corresponding angles to match the other two triangle angles.
3. Conclude the three angles form a straight angle.
Use the worked steps, then substitute the final answer back into the original relationship to confirm it satisfies the prompt.
Simply stating that triangle angles sum to 180 degrees.