  We report measurements of $\sin{2\beta}$ and $\cos{2\beta}$ from a
time-dependent Dalitz plot analysis of $B^{0} \to D^{(*)} h^{0}$ with $D \to
K_{S}^{0} \pi^{+} \pi^{-}$ decays, where the light unflavored and neutral
hadron $h^{0}$ is a $\pi^{0}$, $\eta$, or $\omega$ meson. The analysis is
performed with a combination of the final data sets of the \babar\ and Belle
experiments containing $471 \times 10^{6}$ and $772 \times 10^{6}$ $B\bar{B}$
pairs collected at the $\Upsilon\left(4S\right)$ resonance at the
asymmetric-energy B factories PEP-II at SLAC and KEKB at KEK, respectively. We
measure $\sin{2\beta} = 0.80 \pm 0.14 \,(\rm{stat.}) \pm 0.06 \,(\rm{syst.})
\pm 0.03 \,(\rm{model})$ and $\cos{2\beta} = 0.91 \pm 0.22 \,(\rm{stat.}) \pm
0.09 \,(\rm{syst.}) \pm 0.07 \,(\rm{model})$. The result for the direct
measurement of the angle is $\beta = \left( 22.5 \pm 4.4 \,(\rm{stat.}) \pm 1.2
\,(\rm{syst.}) \pm 0.6 \,(\rm{model}) \right)^{\circ}$. The last quoted
uncertainties are due to the composition of the $D^{0} \to K_{S}^{0} \pi^{+}
\pi^{-}$ decay amplitude model, which is newly established by a Dalitz plot
amplitude analysis of a high-statistics $e^{+}e^{-} \to c\bar{c}$ data sample
as part of this analysis. We find the first evidence for $\cos2\beta>0$ at the
level of $3.7$ standard deviations. The measurement excludes the trigonometric
multifold solution $\pi/2 - \beta = (68.1 \pm 0.7)^{\circ}$ at the level of
$7.3$ standard deviations and therefore resolves an ambiguity in the
determination of the apex of the CKM Unitarity Triangle. The hypothesis of
$\beta = 0^{\circ}$ is ruled out at the level of $5.1$ standard deviations, and
thus CP violation is observed in $B^{0} \to D^{(*)} h^{0}$ decays.
