Raons trigonomètriques
Calcular el valor de les funcions trigonomètriques (sinus, cosinus i tangent) de $x=\dfrac{5\pi}{6}$ rad.
L'angle $\dfrac{5\pi}{6}$ és un angle del segon quadrant, és a dir, $\dfrac{\pi}{2} < \dfrac{5\pi}{6} < \pi$, per tant tenim: $$\sin(x)=\sin(\dfrac{5\pi}{6})=\sin(\pi-\dfrac{5\pi}{6})=\sin(\dfrac{\pi}{6})=\dfrac{1}{2}$$
$$\cos(x)=\cos(\dfrac{5\pi}{6})=-\cos(\pi-\dfrac{5\pi}{6})=-\cos(\dfrac{\pi}{6})=-\dfrac{\sqrt{3}}{2}$$
$$\tan(x)=\tan(\dfrac{5\pi}{6})=-\tan(\pi-\dfrac{5\pi}{6})=-\tan(\dfrac{\pi}{6})=-\dfrac{\sqrt{3}}{3}$$
$$\sin(x)=\dfrac{1}{2}$$
$$\cos(x)=-\dfrac{\sqrt{3}}{2}$$
$$\tan(x)=-\dfrac{\sqrt{3}}{3}$$