Educação Superior::Ciências Exatas e da Terra::MatemáticaThis Demonstration shows some geometric relationships between terms in the contour integral around the origin of f(z)=z^n, nEZ. Note in particular that the complete integral around the origin takes on a nonzero value only when n=-1. In this case the z^n term (green) and the dz term (red) rotate in such in such a way that their product z^ndz (green) points in a fixed direction. In all other cases, the product rotates an integer number of times along the complete contour, resulting in a zero value. The term Lθ in the legend refers to the end-point of the (black) arc of integration