reserve a,b,c,x,y,z for Real;

theorem Th30:
  0 <= a & 0 <= b implies sqrt (a/b) = sqrt a/sqrt b
proof
  assume that
A1: 0 <= a and
A2: 0 <= b;
A3: (sqrt b)^2 = b by A2,Def2;
  (sqrt a)^2 = a by A1,Def2;
  then
A4: (sqrt a/sqrt b)^2 = a/b by A3,XCMPLX_1:76;
A5: 0 <= sqrt b by A2,Def2;
  0 <= sqrt a by A1,Def2;
  hence thesis by A5,A4,Def2;
end;
