In this video lesson, students are introduced to the terms complementary, for describing two angles whose measures add to 90°, and supplementary, for describing two angles whose measures add to 180°. They practice finding an unknown angle given the measure of another angle that is complementary or supplementary. Students realize that many angles share the same vertex as other angles, so they must be precise when naming each angle (MP6) in addition to describing the relationship between pairs of angles.

Grade 7, Episode 22: Unit 7, Lesson 2 | Illustrative Math