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.	$\text{-}\sqrt{3}$	$\text{-} 1$	$\text{-}\dfrac{1}{\sqrt{3}}$	$0$