  We perform a joint likelihood analysis of the power spectra of the 2dF Galaxy
Redshift Survey (2dFGRS) and the cosmic microwave background (CMB) anisotropies
under the assumptions that the initial fluctuations were adiabatic, Gaussian
and well described by power laws with scalar and tensor indices of n_s and n_t.
On its own, the 2dFGRS sets tight limits on the parameter combination Omega_m
h, but relatively weak limits on the fraction of the cosmic matter density in
baryons Omega_b/Omega_m. The CMB anisotropy data alone set poor constraints on
the cosmological constant and Hubble constant because of a `geometrical
degeneracy' among parameters. Furthermore, if tensor modes are allowed, the CMB
data allow a wide range of values for the physical densities in baryons and
cold dark matter. Combining the CMB and 2dFGRS data sets helps to break both
the geometrical and tensor mode degeneracies. The values of the parameters
derived here are consistent with the predictions of the simplest models of
inflation, with the baryon density derived from primordial nucleosynthesis and
with direct measurements of the Hubble parameter. In particular, we find strong
evidence for a positive cosmological constant with a pm 2sigma range of 0.65 <
Omega_Lambda < 0.85, completely independently of constraints on Omega_\Lambda
derived from Type Ia supernovae.
