Simple Equation Set, No Solution



 > maxima
Maxima 5.29.1 http://maxima.sourceforge.net
using Lisp GNU Common Lisp (GCL) GCL 2.6.7 (a.k.a. GCL)
...

eq1:r1*theta = 6*%pi;
eq2:r2*theta = 12*%pi;
eq3:sqrt((r2-r1)^2-3^2) = sqrt(6^2-3^2);
solve([eql1, eq2, eq3],[r1,r2,theta]);

Returns [], but,

subst([r1=6, r2=12, theta=%pi],[eq1, eq2, eq3]);

Returns, [6 %pi = 6 %pi, 12 %pi = 12 %pi, 3 = 3 ]

How do I get Maxima to solve this set?

Tom Dean