cos ( A+B ) - cos ( A-B ) = - 2 sin sin B
Matematika
kristinaandriyani
Pertanyaan
cos ( A+B ) - cos ( A-B ) = - 2 sin sin B
1 Jawaban
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1. Jawaban ahreumlim
Cos ( A+B ) - cos ( A-B )
= (cos A . cos B - sin A . sin B) - (cos A . cos B + sin A . sin B)
= (cos A . cos B) - (sin A . sin B) - (cos A . cos B) - (sin A . sin B)
= - (sin A . sin B) - (sin A . sin B)
= - 2 sin A . sin B (Terbukti)