Triangle Angles Add Up to 180
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Objective
I can prove that the angles inside a triangle add up to 180° using models and find a missing angle in a triangle.
Part 1 of 3
Warm-up video
Khan Academy · 4:28Vetted channel
We don't generate video — this one is by Khan Academy 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 3
Practice
7 questions
Explain in your own words why the angles inside a triangle always add up to 180°.
Draw a triangle and label its angles as A, B, and C. If angle A is 60° and angle B is 80°, what is the measure of angle C?
Part 3 of 3
Exit ticket
Quick comprehension check
“A triangle has angles measuring 60° and 75°. What is the measure of the third angle? A triangle has angles measuring 90° and 20°. What is the measure of the third angle? ”
Sample answer included in the free materials
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