1. Extra 5 pt pass if…. You can find the exact value of cos 75˚ with out a calculator. Good luck!!

2. 5.4 – Sum and Difference Formulas *You need to have these memorized!!

3. Sum and Difference Formulas

4. We will use these formulas to find exact values of trig functions… Ex.1) Find the exact value of cos 75˚

5. Ex.2) Find the exact value of cos π/12 Can you find another way to find the exact value of sin π/12?

6. Ex. 4) Find the exact value of the tan 105˚

7. How would you solve… Ex 5) sin42˚cos12˚-cos42˚sin12˚ Ex 6) sin40˚cos50˚+cos40˚sin50˚ Ex. 7) tan73˚ – tan13˚ 1 + tan73˚tan13˚

8. Prove the cofunction identity using the addition and subtraction formulas… 1.) tan (π/2 – x ) = cot x 2.) sec (π/2 –x) = csc x

9. Verify the following 1.) 2.) cos(x + y)cos(x – y) = cos 2 x - sin 2 y

10. 5.4 – Day 1 HW Pg. 384 #’s 23 – 51 #’s 23,27, 29, 31, 33, 39,41, 45, 51

11. Writing algebraic expressions using the sum and difference formulas… (ex.1) cos(arctan 1 + arccos x)

12. Ex. 2) sin(arctan 2x – arccos x) Try: cos(arccos x – arctan x)

13. More Practice…. HW Day 2 Pg. 385 #’s 17, 19, 23, 35, 43, 57, 63

14. Solving Trig Equations… Ex 1) sin(x + π/4) + sin(x – π/4) = -1 [0, 2π)

15. Ex 2.) sin(x + π/6) – sin(x - π/6) = ½ Ex. 3) tan (x + π) + 2sin(x + π)=0

16. Homework Day #3 Pg. 384 #69-73 odd Quiz 5.4 Study Problems… THE EVENS