Nilai dariCos195°+cos465°+cos330°=
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Nilai dariCos195°+cos465°+cos330°=
1 Jawaban
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1. Jawaban Anonyme
jawab
cos 465 + cos 195 + cos 330=
= (cos 465 + cos 195) + cos 330) =
= 2 cos 1/2(465+195) cos 1/2(465-195) +cos 330
= 2 cos 330 cos 135 + cos 330
= 2 cos (360 - 30) cos (180-45) + cos (360-30)
= 2 cos 30 cos 45 + cos 30
= cos 30 (2 cos 45 + 1)
= 1/2 √3 ( 2 (1/2 √2 ) + 1 )
= 1/2 √3 (√2+ 1)
= 1/2 √6 + 1/2