Pre-Calculus 11 Notes

By: Gen L.




In partnership with Hyperion University, 2023





Lesson 2: Sine Law





What is Sine Law?

Up until this point when we have used the primary trig ratios (), it has only been with right triangles (). However, Trigonometry is not limited to only Right Triangles.

The Sine Law

  • /

Notes / Notation:

    • Find an angle.
    • Find a side.
  • Only use two proportions when solving
  • Must be one full proportion
  • Notation: for side, for angle.
    • : Sine Length Determinant (Sine Law)
    • : Sine Angle Determinant (Sine Law)

Example 1: Side ()

  • Determine the length of .
  1. Define variables.
      • We can determine that
    • We now have a full proportion.
  3. both sides.

Example 1, cont.

  1. Solve

Example 2: Angle ()

  • Determine
  1. Define variables.
    • We have a full proportion.
  3. both sides.

Example 2, cont.

  1. Solve.

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