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Khan Academy (English - US curriculum)
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Khan Academy (English - US curriculum)
Math by grade
Illustrative Mathematics
8th grade (Illustrative Mathematics)
Unit 1: Rigid transformations and congruence
Lesson 16: Parallel lines and the angles in a triangle
Lesson 16: Parallel lines and the angles in a triangle
Angles in a triangle sum to 180° proof
Triangle exterior angle example
Worked example: Triangle angles (intersecting lines)
Finding angle measures using triangles
