Angles & Parallel Lines

An angle measures turn or separation between rays, and intersections and parallel lines create dependable angle relationships.

What you'll learn

  • Interpret an angle as turn between rays rather than ray length.
  • Use full-turn and straight-angle benchmarks of 360° and 180°.
  • Distinguish vertical angles from supplementary adjacent angles.
  • Use corresponding and alternate interior angles only when parallelism is established.
  • Chain angle relationships in triangles and bisected angles.

Before you start

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