Cos is the short version of the trigonometry Cosine() function. This short version is always used in equations and expressions since it takes less space. Used in an equation it might look like

cos x = -0.22
This would be interpreted as "The cosine of x is -0.22". Most mathematicians would speak it as "cosine x equals negative 0.22". (It is sometimes spoken as 'cos' also).

Pages referring to 'cos'

Definition of the cosine function as applied to right triangles in trigonometry
Interactive demonstration of the graph of the cosine function in trigonometry
Definition of the arccos function in trigonometry. The inverse of the cosine function. The angle whose cosine is a given number.
A brief introduction to trigonometry to allow geometry formulas to be calculated. How to claculate sin, cos, tan functions.