Sine and Cosine of Complementary Angles and Special Angles

Building trigonometric basics here will last a mathematical lifetime. Learners expand on the previous lesson in a 36-part series by examining relationships between the sine and cosine of complementary angles. They also review the ratios of the special angles and learn patterns to help remember these ratios.

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CCSS: Designed
Instructional Ideas

  • Use an applet or create a geogebra demonstration to illustrate example #2
  • Create a set of 30-60-90 triangles with known side length; the ratios of sides should become known values
Classroom Considerations

  • Some of the symbols may be confusing for pupils; substitute actual values for angles and/or side lengths

  • Emphasizes the ratios for 30-, 60-, 45-, and 90-degree angles
  • Includes a teacher guide with suggestions for differentiation 

  • None