Interior Angles of Triangles
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Objective
I can prove that the sum of the interior angles of a triangle is 180 degrees.
Part 1 of 4
Warm-up video
Kristen Watson · 4:24
We don't generate video — this one is by Kristen Watson on YouTube. The practice questions and exit ticket below were drafted by AI for this objective, and every question is editable in the teacher guide.
Part 2 of 4
Key concepts
3 concepts
- 1
The Triangle Sum Theorem states that the sum of the three interior angles of any triangle will always add up to 180 degrees.
- 2
If a triangle has angles A, B, and C, then the equation A + B + C = 180 can be used to solve for missing angle measurements.
- 3
When solving for a variable within angle expressions, remember to combine like terms before isolating the variable using inverse operations.
Part 3 of 4
Practice
10 questions
The Triangle Sum Theorem states that the sum of the interior angles of any triangle is always equal to what?
In triangle PQR, angle P measures 60 degrees and angle Q measures 80 degrees. What is the measure of angle R?
Part 4 of 4
Exit ticket
Quick comprehension check
“In triangle ABC, ∠A measures 60°, ∠B measures 80°. What is the measure of ∠C?”
Sample answer included in the free materials
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