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

theorem
  0 < a implies sqrt a/a = 1/sqrt a
proof
  assume
A1: 0 < a;
  then sqrt a <> 0^2 by Def2;
  hence sqrt a/a = (sqrt a)^2/(a*sqrt a) by XCMPLX_1:91
    .= (1*a)/(sqrt a*a) by A1,Def2
    .= 1/sqrt a by A1,XCMPLX_1:91;
end;
