4.sin 30°-5cotan 120°+cos210°
Matematika
tegesmoshadi1082
Pertanyaan
4.sin 30°-5cotan 120°+cos210°
1 Jawaban
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1. Jawaban Hyeolkim12
Sin 30° = 1/2
Cotan 120° = Cotan (180° - alfa) = -cotan alfa
Cotan 120° = cotan (180° - 60°) = - cotan alfa
Cotan 60° = - 1/3 akar 3
Cos 210° = cos (180° + alfa) = - cos alfa
Cos 210° = cos (180° + 30°) = - cos alfa
Cos 30° = - 1/2 akar 3
Sin 30° - 5cotan 120° + cos 210°
= 1/2 - 5x1/3 akar 3 + (- 1/2 akar 3)
= 1/2 - 5/3 akar 3 - 1/2 akar 3
= 1/2 - 10/6 akar 3 - 3/6 akar 3
= 1/2 - 7/6 akar 3