cosine at multiples of straight angle

Everybody remembers the cosine values

$$\cos 0=1,\cos (\pm \pi )=-1,\cos (\pm 2\pi )=1,\cos (\pm 3\pi )=-1,\mathrm{\dots }$$

The thing can be concisely expressed as the

$$\cos n\pi ={(-1)}^n$$

for each integer $n$.  The values of sine at the same angles are simply 0.

Title	cosine at multiples of straight angle
Canonical name	CosineAtMultiplesOfStraightAngle
Date of creation	2013-03-22 15:45:40
Last modified on	2013-03-22 15:45:40
Owner	pahio (2872)
Last modified by	pahio (2872)
Numerical id	6
Author	pahio (2872)
Entry type	Definition
Classification	msc 26A09
Related topic	multiple
Related topic	ComplexSineAndCosine
Related topic	HigherOrderDerivativesOfSineAndCosine
Related topic	FourierSineAndCosineSeries
Related topic	GeneralAssociativity
Related topic	ValueOfRiemannZetaFunctionAtS4
Related topic	ValueOfDirichletEtaFunctionAtS2