csc = hypotenuse / opposite = 13/12
sec = hypotenuse / adjacent = -13/5
cot = adjacent / opposite = -5/12
If you stare at these long enough, massage them and roll them around,
(and remember that the hypotenuse is always positive in the circle), it
eventually dawns on you that
adjacent = -5
opposite = 12
hypotenuse = 13
Draw the angle in the circle, and the end of it is in the second quadrant,
at (-5, 12) .
