cos(a) sin(a) ------ - cos(a) - ------ + 1 1 cos(a)
sin(a) 1 - ------ cos(a)
1.0 - sin(a)/cos(a)
-sin(a) + cos(a) ---------------- cos(a)
cos(a) sin(a) 1 - cos(a) + ------ - ------ 1 cos(a)
1 - tan(a)