Jawabanmu

2014-03-25T12:17:58+07:00
Sinαsinβ= \frac{1}{4}
cos(α-β)=cosαcosβ + sinαsinβ
(α+β)= \frac{ \pi }{3} = 60

cos(α+β)=cosαcosβ - sinαsinβ
cos60=cosαcosβ -  \frac{1}{4}
 \frac{1}{2} =cosαcosβ  -  \frac{1}{4}
cosαcosβ= \frac{3}{4}

cos(α-β)=cosαcosβ + sinαsinβ
cos(α-β)= \frac{3}{4} + \frac{1}{4} = 1 [/tex]

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