Teori

# Cosinus av en standardvinkel

Cosinusvärdet för en standardvinkel kan läsas direkt ur en tabell med exakta trigonometriska värden. Tabellen visar bland annat att $\cos\left( \frac{\pi}{3} \right)=\frac{1}{2}.$

$v$ (grader) $0^\circ$ $30^\circ$ $45^\circ$ $60^\circ$ $90^\circ$ $120^\circ$ $135^\circ$ $150^\circ$ $180^\circ$
$v$ (radianer) $0$ $\dfrac{\pi}{6}$ $\dfrac{\pi}{4}$ $\dfrac{\pi}{3}$ $\dfrac{\pi}{2}$ $\dfrac{2\pi}{3}$ $\dfrac{3\pi}{4}$ $\dfrac{5\pi}{6}$ $\pi$
$\sin(v)$ $0$ $\dfrac{1}{2}$ $\dfrac{1}{\sqrt{2}}$ $\dfrac{\sqrt{3}}{2}$ $1$ $\dfrac{\sqrt{3}}{2}$ $\dfrac{1}{\sqrt{2}}$ $\dfrac{1}{2}$ $0$
$\cos(v)$ $1$ $\dfrac{\sqrt{3}}{2}$ $\dfrac{1}{\sqrt{2}}$ $\dfrac{1}{2}$ $0$ $\text{-}\dfrac{1}{2}$ $\text{-}\dfrac{1}{\sqrt{2}}$ $\text{-}\dfrac{\sqrt{3}}{2}$ $\text{-}1$
$\tan(v)$ $0$ $\dfrac{1}{\sqrt{3}}$ $1$ $\sqrt{3}$ Odef. $\text{-}\sqrt{3}$ $\text{-} 1$ $\text{-}\dfrac{1}{\sqrt{3}}$ $0$