[en] We evaluate the contribution to the X(3872) width from a triangle mechanism in which the X decays into D${}^{\text{â<!-- ?? -->}\text{ˆ<!-- ?? -->}\text{—<!-- ??? -->}0}$${\stackrel{¯<!--\; ??\; -->}{D}}^0$ - cc, then the D${}^{\text{â<!-- ?? -->}\text{ˆ<!-- ?? -->}\text{—<!-- ??? -->}0}$(${\stackrel{¯<!--\; ??\; -->}{D}}^{\text{â<!-- ?? -->}\text{ˆ<!-- ?? -->}\text{—<!-- ??? -->}0}$) decays into D${}^0$π${}^0$ (${\stackrel{¯<!--\; ??\; -->}{D}}^0$π${}^0$) and the D${}^0$${\stackrel{¯<!--\; ??\; -->}{D}}^0$ fuse to produce π${}^{+}$π${}^{-<!--\; ???\; -->}$. This mechanism produces an asymmetric peak from a triangle singularity in the π${}^{+}$π${}^{-<!--\; ???\; -->}$ invariant mass with a shape very sensitive to the X mass. We evaluate the branching ratios for a reaction where this effect can be seen in the B${}^{-<!--\; ???\; -->}$ → K${}^{-<!--\; ???\; -->}$π${}^0$π${}^{+}$π${}^{-<!--\; ???\; -->}$ reaction and show that the determination of the peak in the invariant mass distribution of π${}^{+}$π${}^{-<!--\; ???\; -->}$ is all that is needed to determine the X mass. Given the present uncertainties in the X mass, which do not allow to know whether the D${}^{\text{â<!-- ?? -->}\text{ˆ<!-- ?? -->}\text{—<!-- ??? -->}0}$${\stackrel{¯<!--\; ??\; -->}{D}}^0$ state is bound or not, measurements like the one suggested here should be most welcome to clarify this issue.