Berapakah nilai sin 120°?
Jawaban:√3/2
Dari rumus trignometrik
Sin (90 + x) = cos x
Jadi sin 120° dapat ditulis sebagai
Sin (90°+ 30°) = cos 30°
Nilai sin
sin 0° = (0/4) = 0
sin 30° = (1/4) =
sin 45° = (2/4) = 1/√2
sin 60° = 3/4 = 3/2
cos 90° = (4/4) = 1
Nilai Cos
cos 0° = (4/4) = 1
cos 30° = (3/4) = 3/2
cos 45° = (2/4) = 1/√2
cos 60° = (1/4) = 1/2
cos 90° = (0/4) = 0
Dari daftar nilai cos di atas
Cos 30° = 3/2
Jadi
Sin (120°) = Sin (90°+ 30°) = cos 30° = 3/2