  We report measurements of the superconducting transition temperature, $T_c$,
in CoO/Co/Cu/Co/Nb multilayers as a function of the angle $\alpha$ between the
magnetic moments of the Co layers. Our measurements reveal that $T_c(\alpha)$
is a nonmonotonic function, with a minimum near $\alpha={\pi}/{2}$. Numerical
self-consistent solutions of the Bogoliubov - de Gennes equations
quantitatively and accurately describe the behavior of $T_c$ as a function of
$\alpha$ and layer thicknesses in these superconductor / spin-valve
heterostructures. We show that experimental data and theoretical evidence agree
in relating $T_c(\alpha)$ to enhanced penetration of the triplet component of
the condensate into the Co/Cu/Co spin valve in the maximally noncollinear
magnetic configuration.
