  We present U, B and V light curves (taken from the literature) of the low
mass X-ray binary Cygnus X-2. The ``lower envelope'' of the light curves folded
on the orbital period are ellipsoidal. We fit an ellipsoidal model to the lower
envelopes of the B and V light curves to derive inclination constraints. If we
assume the accretion disc is steady-state where its radial temperature profile
goes as T(r) \propto r^{-3/4}, we find an inclination of i = 62.5 +/- 4 deg.
However, the predicted ratio of the disc flux to the total flux in B (the
``disc fraction'') is larger than what is observed (about 0.55 compared to <
0.3). If we use a flatter radial temperature profile of the disc expected for
strongly irradiated discs (T(r) \propto r^{-3/7}), then we find an inclination
of i = 54.6 deg and a disc fraction in B of approximately 0.30. However, in
this case the value of chi^2 is much larger (48.4 with 36 degrees of freedom
compared to 40.9 for the steady-state case). Adopting i = 62.5 +/- 4 deg and
using a previous determination of the mass ratio (q = M_c/M_x = 0.34 +/- 0.04)
and the optical mass function (f(M) = 0.69 +/- 0.03 solar masses), we find that
the mass of the neutron star is M_x = 1.78 +/- 0.23 solar masses and the mass
of the secondary star is M_c = 0.60 +/- 0.13 solar masses. We derive a distance
of d = 7.2 +/- 1.1 kpc, which is significantly smaller than a recent distance
measurement of d = 11.6 +/- 0.3 kpc derived from an observation of a type I
radius-expansion X-ray burst, but consistent with earlier distance estimates.
(abridged)
