Precalculus
Simplifying with Sum &
Difference Identities
Name: _______________________________Period:______
Evaluate.
1. sin75 cos15  cos75 sin15
2π
π
 tan
3
12
3.
2π
π
1  tan
tan
3
12
tan
2. sin
4π
π
4π
π
cos  cos
sin
3
3
3
3
4. cos220 cos50  sin220 sin50
Use the sum and difference identities to find exact values for each of the following.
5. tan75
7. cos
π
12
6. sin15
8. sin
5π
12
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Precalculus
Use the sum & difference identities to simplify the given expression.
9. cos25 cos15  sin25 sin15
11.
tan325  tan86
1  tan325 tan86
13. sin 3x  cos 2x   cos 3x  sin 2x 
10. sin140 cos50  cos140 sin50
12. cos
7π
π
7π
π
cos  sin
sin
10
10
10
10
14. cos 2x  cos  x   sin 2x  sin  x 
Express in terms of sin x, cos x, tan x, or cot x.
15. sin  x  90
16. tan 180  x 
π

17. cos   x 
2

18. cot  x  2π 
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