strange answers



I started to play around with maxima, and there are strange things that 
happen (I used a clean maxima as far as I can see):

11111111111111111111111111111111111111111111111111111111111111111

(C1) solve((COS(b)^2*SINH(b)^2-TAN(a)^2*COSH(b)^2*SIN(b)^2)^2,a);

SOLVE is using arc-trig functions to get a solution.
Some solutions will be lost.
				        %PI
(D1) 				   [a =------]
				          2
(C2) b;

(D2) 				       b

111111111111111111111111111111111111111111111111111111111111111111
I asked for b to show that b has no value (and I cleaned up the 2-dim output, 
it wouldn't copy well).

222222222222222222222222222222222222222222222222222222222222222222

(C3) solve(tan(a)=b,a);


SOLVE is using arc-trig functions to get a solution.
Some solutions will be lost.
(D3) 				 [a = ATAN(b)]
(C4) solve(tan(a)=sin(b),a);

(D4) 			   [SIN(a) = COS(a) SIN(b)]

222222222222222222222222222222222222222222222222222222222222222222

Why's that? The manual says

     In the case where E is a
     polynomial in some function of the variable to be solved for, say
     F(X), then it is first solved for F(X) (call the result C), then
     the equation F(X)=C can be solved for X provided the inverse of
     the function F is known.
so why wouldn't maxima do in C4 what it did in C3?

3333333333333333333333333333333333333333333333333333333333333333333
(C5) solve([%E^a*COS(b) = SIN(a)*COSH(b),%E^a*SIN(b) = 
COS(a)*SINH(b),SIN(a)^2+COS(a)^2 = 1],[exp(a),sin(a),cos(a)]);

		a	         %R1 COS(b)	       %R1 SIN(b)
(D5) 	    [[%E  = %R1, SIN(a) = ----------,        COS(a) = ----------------]]
				COSH(b)	        SINH(b)
3333333333333333333333333333333333333333333333333333333333333333333

???????????

Jurgen