|   | 1 |  initial version  | 
The function solve aims at finding solutions symbolically, and it seems that Sage is not able to do it for your equation. If you want to solve your equation numerically, you can use find_root as follows:
sage: find_root(1/3*x + sin(2*x)-1,0,1)
0.49428348982550824
sage: find_root(1/3*x + sin(2*x)-1,1,2)
1.261800196654962
|   | 2 |  No.2 Revision  | 
The function solve aims at finding solutions symbolically, and it seems that Sage is not able to do it for your equation. If you want to solve your equation numerically, you can use find_root as follows:
sage: find_root(1/3*x + sin(2*x)-1,0,1)
sin(2*x) - 1, 0, 1)
0.49428348982550824
sage: find_root(1/3*x + sin(2*x)-1,1,2)
sin(2*x) - 1, 1, 2)
1.261800196654962
|   | 3 |  No.3 Revision  | 
The function solvesolve()find_rootfind_root()
sage: find_root(1/3*x + sin(2*x) - 1, 0, 1)
0.49428348982550824
sage: find_root(1/3*x + sin(2*x) - 1, 1, 2)
1.261800196654962
 Copyright Sage, 2010. Some rights reserved under creative commons license. Content on this site is licensed under a Creative Commons Attribution Share Alike 3.0 license.
 
                
                Copyright Sage, 2010. Some rights reserved under creative commons license. Content on this site is licensed under a Creative Commons Attribution Share Alike 3.0 license.