1. Pre-AP Pre-Calculus Chapter 5, Section 3
Sum and Difference Identities

2. Use the given triangle to derive the formulas for sin 𝛼+𝛽 and cos 𝛼+𝛽1 𝛼 𝛽

3. Use the given triangle to derive the formulas for sin 𝛼−𝛽 and cos 𝛼−𝛽1 𝛼 𝛽

4. Cosine of a Sum or Difference

5. Sine of a Sum or Difference

6. Using the Sum/Difference Formulas
Write each of the following expressions as the sine or cosine of an angle.
sin 22° cos 13° + cos 22° sin 13°
cos 𝜋 3 cos 𝜋 4 + sin 𝜋 3 sin 𝜋 4
sin 𝑥 sin 2𝑥 − cos 𝑥 cos 2𝑥

7. Find the exact value of each expression.
sin 105°
cos 7𝜋 12
sin 𝜋 12

8. Find the exact value of each expression.
sin 30° cos 60° − cos 30° sin 60°
cos 120° cos 45° − sin 120° sin 45°

9. Let’s Practice #2
Write the expression as the sine, cosine, or tangent of an angle.
cos 94° cos 18° + sin 94° sin 18°

10. Ch 5.3 Homework
Pg. 468 – 469, #’s: 1, 6, 14, 17, 20, 31 – 34, 48, 50
11 total problems
Gray book: pg