Issolvi cos(7pi/6)

$$\cos ( \frac{ 7 \pi }{ 6 } )$$

Evalwa

$$-\frac{\sqrt{3}}{2}\approx -0.866025404$$

Passi tas-Soluzzjonijiet

Uża \cos(x+y)=\cos(x)\cos(y)-\sin(y)\sin(x) fejn x=\pi u y=\frac{\pi }{6} biex tikseb ir-riżultat.

$$\cos(\pi +\frac{\pi }{6})=\cos(\pi )\cos(\frac{\pi }{6})-\sin(\frac{\pi }{6})\sin(\pi )$$

Ikseb il-valur ta’ \cos(\pi ) mit-tabella tal-valuri trigonometriċi.

$$-\cos(\frac{\pi }{6})-\sin(\frac{\pi }{6})\sin(\pi )$$

Ikseb il-valur ta’ \cos(\frac{\pi }{6}) mit-tabella tal-valuri trigonometriċi.

$$-\frac{\sqrt{3}}{2}-\sin(\frac{\pi }{6})\sin(\pi )$$

Ikseb il-valur ta’ \sin(\frac{\pi }{6}) mit-tabella tal-valuri trigonometriċi.

$$-\frac{\sqrt{3}}{2}-\frac{1}{2}\sin(\pi )$$

Ikseb il-valur ta’ \sin(\pi ) mit-tabella tal-valuri trigonometriċi.

$$-\frac{\sqrt{3}}{2}-\frac{1}{2}\times 0$$

Agħmel il-kalkoli.

$$-\frac{\sqrt{3}}{2}$$