jika A + B = radian/3 dan cos A cos B = 5/8, nilai cos (A-B) =
Matematika
endi19fian
Pertanyaan
jika A + B = radian/3 dan cos A cos B = 5/8, nilai cos (A-B) =
1 Jawaban
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1. Jawaban ErikCatosLawijaya
Materi : Trigonometri
Pembahasan :
A + B = 180/3
A + B = 60°
Cos (A + B) = Cos 60°
Cos (A + B) = 1/2
Cos A . Cos B - Sin A . Sin B = 1/2
5/8 - Sin A . Sin B = 1/2
Sin A . Sin B = 5/8 - 1/2
Sin A . Sin B = 5/8 - 4/8
Sin A . Sin B = 1/8
Maka...
Cos (A - B)
= Cos A . Cos B + Sin A . Sin B
= 5/8 + 1/8
= 6/8
= 3/4