theorem Th02:
  ra * N = (ra * 1.(F_Real,3)) * N
  proof
    width 1.(F_Real,3) = 3 by MATRIX_0:24; then
A1: width 1.(F_Real,3) = len N by MATRIX_0:24;
    ra * N = ra * (1.(F_Real,3) * N) by MATRIX_3:18;
    hence thesis by A1,MATRIX15:1;
  end;
