Simple "solve" question



Hello all,
	I have a simple(ish) question about solve. I have an equation,  
called "test" I want to solve "test" for the value "fl". I know the  
values "r" and "c." Likewise, I actually also know the proper value  
for "fl", but I can't get Maxima to give it to me.

/*-------------*/
/* My test equation */
test:6096*tan((2*atan(c/(2*fl)))/r) / (tan(((1/60)*(%pi/180))));
/* solve for fl ... */
solve(test=6096,fl);

/* what if we give c and r values? */
subst([c=7.176,r=3264],test);
solve(test=6096,fl);

/* still cant solve!, but I know that there is a solution.. */
subst([c=7.176,r=3264,fl=6.98149293282488],test);
float(%);
/*-------------*/


Is there something that I am missing, some built-in variable that I  
should change.

Thanks
-Greg

---------
(%i13) /* My test equation */
test:6096*tan((2*atan(c/(2*fl)))/r) / (tan(((1/60)*(%pi/180))));
                                              c
                                      2 atan(----)
                                             2 fl
                             6096 tan(------------)
                                           r
(%o13)                      ----------------------
                                        %pi
                                   tan(-----)
                                       10800
(%i14) /* solve for fl ... */
solve(test=6096,fl);
(%o14)                                []
(%i15) /* what if we give c and r values? */
subst([c=7.176,r=3264],test);
                                            3.588
                                       atan(-----)
                                             fl
                              6096 tan(-----------)
                                          1632
(%o15)                       ---------------------
                                        %pi
                                   tan(-----)
                                       10800
(%i16) solve(test=6096,fl);
(%o16)                                []
(%i17) /* still cant solve!, but I know that there is a solution.. */
subst([c=7.176,r=3264,fl=6.98149293282488],test);
                                1.773254570041446
(%o17)                         -----------------
                                        %pi
                                   tan(-----)
                                       10800
(%i18) float(%);
(%o18)                              6096.0
(%i19)