We present results of a new analysis campaign, which combines the final data samples collected by the B factory experiments \sbabar\ and Belle in single physics analyses to achieve a unique sensitivity in time-dependent \CP\ violation measurements. The data samples contain $(471 \pm 3) \times 10^6 ~B \bar B$ pairs recorded by the \sbabar\ detector and $(772 \pm 11) \times 10^6 ~ B \bar B$ pairs recorded by the Belle detector in $e^+e^-$ collisions at the center-of-mass energies corresponding to the mass of the $\Upsilon(4S)$ resonance at the asymmetric-energy $B$ factories PEP-II at SLAC and KEKB at KEK. We present a measurement of $\sin 2\beta$ and $\cos 2\beta $ by a time-dependent Dalitz plot analysis of $B^0 \ra D^{(*)} h^0$ with $D \ra K^0_S \pi^+\pi^-$ decays. A first evidence for $\cos 2\beta >0$, the exclusion of trigonometric multifold solutions of the Unitarity Triangle and an observation of \CP\ violation are reported.