1. Warm-up:
Find sin(195o)
HW : pg. 501(1 – 18)

2. HW Answers: pg. 490(1 – 4, 7 – 16, , 45 – 48)

3. Ch 5.5: Double – Angle Formulas
Objective:
Use Double – Angle Formulas

4. Double Angle Formulas

5. Solving a Trigonometric Equation
Find all the solutions of 2 cosx + sin 2x = 0
2 cosx + sin 2x = 0
2 cosx + 2sinxcosx = 0
2 cosx(1 + sinx) = 0
cosx = 0, sinx = 0

6. Evaluating Functions Involving Double Angles
Ex: Find the sin2Ө, cos2Ө, and tan2Ө if

7. Find sin(x + y), cos(x + y) and tan(x + y) given
sinx = 12/13, cosx < 0 siny = -4/5 , 3π/2 < y < 2π 3 13 12 -4 5 -5
Sin(x + y) = sinxcosy + cosxsiny
cos(x + y) = cosxcosy – sinxsiny

8. Find sin2x and cos2y given
sinx = -15/17, π < x < 3π/ siny = 4/5 , cosy < 0 -8 5 4
-15 17 -3

9. Solve 2cos(2x) + 2sin2x = 1 for [0, 2)

10. Sneedlegrit:
Find sin(15o)
HW : pg. 501(1 – 18)