5.4 Sum and Difference Identities
Sum Identities
Difference Identities
Example 1
Evaluate without a calculator
sin(105°)
Example 2
Evaluate without a calculator
tan(75°)
Example 3
Evaluate without a calculator
cos(15°)
Example 4
Evaluate without a calculator
sin(15°)
Example 5
Condense and simplify
tan(32°) + tan(13°)
1 - tan(32°)tan(13°)
Example 6
Condense and simplify
tan(6x) - tan(7x)
1 + tan(6x)tan(7x)
Example 7
Condense and simplify
sin(x)sin(3x) - cos(x)cos(3x)
Example 8
Condense and simplify
cos(y)cos(8y) + sin(y)sin(8y)
Use a sum or difference identity to verify:
sin(π/2 - x) = cos(x)
Homework
pg. 341 #1-4
12-22 (evens)
Classwork
pg. 341 #32-38