If is an acute angle, then we can draw
a right triangle, as in (A) of
the figure below. The side
opposite the angle is labeled *b*, the side
adjacent to is labeled *a* and the hypotenuse
is labeled *c*. In (B), we have placed
the vertex *A* at the origin, and the adjacent side on the *x*-axis.
The vertex *B* is at the point (*a*,*b*).

acute.epsAlternate definitions for and are:

Note that when *c*=1, the point *B*(*a*,*b*) lies on the
unit circle, and is
the second coordinate of the point *B*(*a*,*b*), while is the first coordinate of this point.
Thus these alternate definitions are consistent with the old
definitions of sine and cosine.

Wed Apr 21 08:17:28 EDT 1999