Matematika

Pertanyaan

cos 105° x cos 15

bantuannya

1 Jawaban

  • = 1/2 (2 cos 105 cos 15)
    = 1/2 (cos (105+15) + cos (105-15))
    = 1/2 (cos (120+90))
    = 1/2 ( -1/2 + 0 )
    = -1/4

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