Diketahui \(\theta\) adalah suatu sudut yang lebih besar dari \(360^{\circ}\) dan \(\alpha\) adalah suatu sudut yang kurang dari \(360^{\circ}\)
\(\color{blue}\sin \theta = \sin (n\cdot 360^{\circ} + \alpha) = \sin \alpha\)
\(\color{blue}\cos \theta = \cos (n\cdot 360^{\circ} + \alpha) = \cos \alpha\)
\(\color{blue}\tan \theta = \tan (n\cdot 360^{\circ} + \alpha) = \tan \alpha\)
\(n\) = bilangan bulat positif
CONTOH SOAL
Soal 1
Tentukan nilai \(\sin 750^{\circ}\)
\(\sin 750^{\circ} = \sin (2\cdot 360^{\circ} + 30^{\circ})\)
\(\sin 750^{\circ} = \sin 30^{\circ}\)
\(\sin 750^{\circ} = \frac{1}{2}\)
Soal 2
Tentukan nilai \(\cos 1125^{\circ}\)
\(\cos 1125^{\circ} = \cos (3\cdot 360^{\circ} + 45^{\circ})\)
\(\cos 1125^{\circ} = \cos 45^{\circ}\)
\(\cos 1125^{\circ} = \frac{1}{2}\sqrt{2}\)
Soal 3
Tentukan nilai \(\tan 2940^{\circ}\)
\(\tan 2940^{\circ} = \tan (8\cdot 360^{\circ} + 60^{\circ})\)
\(\tan 2940^{\circ} = \tan 60^{\circ}\)
\(\tan 2940^{\circ} = \sqrt{3}\)
Soal 4
Tentukan nilai \(\sin 1650^{\circ}\)
\(\sin 1650^{\circ} = \sin (4\cdot 360^{\circ} + 210^{\circ})\)
\(\sin 1650^{\circ} = \sin 210^{\circ}\)
\(\sin 1650^{\circ} = \sin (180^{\circ} + 30^{\circ})\)
\(\sin 1650^{\circ} = \sin 30^{\circ}\)
\(\sin 1650^{\circ} = \frac{1}{2}\)
Soal 5
Tentukan nilai \(\cos 4620^{\circ}\)
\(\cos 4620^{\circ} = \cos (12\cdot 360^{\circ} + 300^{\circ})\)
\(\cos 4620^{\circ} = \cos 300^{\circ}\)
\(\cos 4620^{\circ} = \cos (360^{\circ} \:-\: 60^{\circ})\)
\(\cos 4620^{\circ} = \cos 60^{\circ}\)
\(\cos 4620^{\circ} = \frac{1}{2}\)