  We investigate the sensitivity with which two angles of the "flat" unitarity
triangle, defined by $V_{ub}^* V_{us} + V_{cb}^* V_{cs} + V_{tb}^* V_{ts} =0$,
can possibly be measured directly at FCCee. We show that the measured errors on
the angle $\alpha_s = \arg(- V_{ub}^* V_{us} /V_{tb}^* V_{ts})$ and $\beta_s =
\arg(-V_{tb}^* V_{ts} / V_{cb}^* V_{cs})$ should be better than $0.4^\circ$ and
$0.035^\circ$, respectively. These measurements, combined with the measurement
of the 3rd angle $\gamma_s = \arg(- V_{cb}^* V_{cs}/ V_{ub}^* V_{us})$,
discussed in a different paper, will contribute to probe further the
consistency of the CP sector of the Standard Model with unprecedented level of
accuracy.
