  We express the matrix elements of the density matrix of the qutrit state in
terms of probabilities associated with artificial qubit states. We show that
the quantum statistics of qubit states and observables is formally equivalent
to the statistics of classical systems with three random vector variables and
three classical probability distributions obeying special constrains found in
this study. The Bloch spheres geometry of qubit states is mapped onto triangle
geometry of qubits. We investigate the triada of Malevich's squares describing
the qubit states in quantum suprematism picture and the inequalities for the
areas of the squares for qutrit (spin-1 system). We expressed quantum channels
for qutrit states in terms of a linear transform of the probabilities
determining the qutrit-state density matrix.
