This chapter contains a significant sequence of the properties for
the real functions of real arguments, also important for the introduction of the
fundamental trigonometric functions. Here are included only the properties
considered appropriate for defining and describing the essential trigonometric
functions. the range of these representative qualities is larger and it is also
suggested by the selective bibliography mentioned further on.
Keywords: real function of real argument, graphic, surjective, injective,
bijective, inverse, geometric characterization, bounded, monotonous,
periodic, centers(axes) of symmetry, Darboux property, continuous,
convex(concave).
