10-3 Review

This weekend I am going to go over the material that we learned in chapter 10 section 3. These two sections contain the same types of problems as sections 1 and 2. The only difference is that now you are going to use double angle and half angle formulas to solve the trig equations. You need to follow the same steps that you followed in the previous sections of this chapter.

*Always remember to replace, not plug in.

Formulas:
1. sin 2a= (2 sin a) (cos a)
2. cos 2a= (cos^2 a) – (sin^2 a)
3. cos 2a= 1- 2 sin^2 a
4. cos 2a= 2 cos^2 a -1
5. tan 2a= ( 2 tan a) / ( 1- tan^2 a)
6. sin a/2= +/- sq. root of ((1 – cos a) / (2))
7. cos a/2= +/- sq. root of (( 1+ cos a) / (2))
8. tan a/2= +/- sq. root of (( 1- cos a) / ( 1+cos a))
9. tan a/2= +/- (( sin a) / ( 1+ cos a))
10. tan a/2= +/- (( 1- cos a) / (sin a))

Example: Simplify cos^2(4A) – sin^2(4A)
• Cos 2(4A)
• Cos 8A

-Braxton