Chapter 5

Figuring out which functions to use when solving an identity is hard and if you make the wrong choice you run out of time. solving equations when theta is double or halved or tripled that don't work in the formula are also confusing.

My feelings on chapter 5

I feel that the most challenging part of chapter 5 are the sum-difference formulas.

5.4 Sum and difference formulas

Sum and difference formulas

Sin:

sin(u+v) = sin u cos v + cos v sin u
sin(u-v) = sin u cos v - cos v sin u

Cos:

cos(u+v) = cos u cos v - sin u sinv
cos(u-v) = cos u cos v + sin u sinv

Tan:

tan(u+v) = tan u + tan v / 1-tan u tan v
tan(u-v) = tan u - tan v / 1+tan u tan v

Example:

Find the exact cos of 75 degrees.

cos75
= cos(30+45)
= cos30cos45 - sin30sin45
= .259

By Jake Badalamenti