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5.4 Sum and Difference Formulas
In this section students will use sum and difference formulas to evaluate trigonometric functions, verify identities, and solve trigonometric equations.
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Section 5.4, Sum and Difference Formulas, pg. 368
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Example 1
Find the exact value of cos75
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Section 5.4, Sum and Difference Formulas, pg. 368
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Example 2
Find the exact value of sin12
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Section 5.4, Sum and Difference Formulas, pg. 368
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Example 3
Find the exact value of sin(u+v) given
, where and
where
sinu 4
50
2 u
cosv
12
13 2
v
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Section 5.4, Sum and Difference Formulas, pg. 368
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Example 5
Prove the cofunction identity cos( ) sin2
x x
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Section 5.4, Sum and Difference Formulas, pg. 368
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Example 6
Simplify the expression.
a. b.cos( )
3
2tan( ) 3
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Section 5.4, Sum and Difference Formulas, pg. 368
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Example 7
Find all solutions of in the interval
sin( ) sin( )x x 4 4
1
[ , )0 2