Complements and Supplements: Finding Missing Angles
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Students will identify complementary and supplementary angle relationships and apply them to solve for unknown angle measures in numeric and algebraic contexts.
Lesson Overview
Students progress from identifying complementary and supplementary angle pairs to solving multi-step algebraic equations involving angle relationships, including real geometric contexts with parallel lines and angle bisectors.
Materials
- Vertical whiteboards or chart paper
- Dry-erase markers and erasers
- Rulers
- Printed reference card (90° and 180° anchor)
Scaffolded Task Progression
1. Find their sum.
2. Are these angles complementary, supplementary, or neither?
[ Interactive graph / diagram, available in the full lesson ]
1. Find their sum.
2. Are these angles complementary, supplementary, or neither?
[ Interactive graph / diagram, available in the full lesson ]
Find its complement.
[ Interactive graph / diagram, available in the full lesson ]
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