On Sat, 10 Sep 2005 02:42:02 -0700, "Mark D T Jones" <Mark D T
wrote:

I can take tan (A) =b of a angle, to produce a fraction, but can't work back
to an angle using tan^-1 (b)=A



Look up the definition of arctangent, then look at HELP for the ATAN worksheet
function. There is also ACOS and ASIN available to you.

ATAN

Returns the arctangent, or inverse tangent, of a number. The arctangent is the
angle whose tangent is number. The returned angle is given in radians in the
range -pi/2 to pi/2.


--ron