reserve x,x0, r,r1,r2 for Real,
      th for Real,

  rr for set,

  rseq for Real_Sequence;

theorem Th93:
  arcsec1|[.1,sqrt 2.] is continuous
proof
  set f = sec | [.0,PI/4.];
  f|[.0,PI/4.] = f & (f|[.0,PI/4.])"|(f.:[.0,PI/4.]) is continuous by Lm29,Lm37
,FCONT_1:47,RELAT_1:72;
  then arcsec1|[.1,sqrt 2.]|[.1,sqrt 2.] is continuous by Th41,Th49,RELAT_1:115
;
  hence thesis by FCONT_1:15;
end;
