This worksheet presents a little procedure (named "retas") developed so as to take advantage of the graphical and derivation capabilities of Maple8.0 software, mainly for educational purposes. The parametres of "retas" are in this order:

1 - A one-variable function in the form x->f(x) (or any other independent variable).
2 - The initial ni and final nf value of the independent variable.
3 - The distance p between the different tangent straight lines to be plotted.
4 - A parameter named r that regulates the range of visualization of the function f on the Y-axis (ymáx=r.nf and ymin=r.ni).

From these data "retas" plots the function f, its first derivate df/dx and various tangent straight lines to f at discrete points (separated by a distance p) of the sub-domain of f defined by ni<x<nf. The tangent straight lines size can be regulated inside the code in spite of the default value (15% of the range nf-ni) is considered enough for visaulization effects.