The Generalization
We are now in a position to define the trig function of any angle, acute or
otherwise! It is so important that we enclose it in a box:
As noted in the examples above with the angles that lie on the axes, one or
both of the legs of the right triangle will be viewed as ``negative'' if
one or both of the
coordinates (x,y) of the point in question are negative.
James A. Sellers