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