Matematika

Pertanyaan

Nilai dariCos195°+cos465°+cos330°=

1 Jawaban

  • 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

Pertanyaan Lainnya