reserve a,b,c,d for Real;

theorem Th7:
  a <= b implies for t1,t2 being Point of Closed-Interval-TSpace(a,b)
  for s being Point of Closed-Interval-TSpace(0,1) holds
  L[01](t1,t2).s = (t2 - t1)*s + t1
proof
  assume
A1: a <= b;
  let t1,t2 be Point of Closed-Interval-TSpace(a,b);
  let s be Point of Closed-Interval-TSpace(0,1);
  thus L[01](t1,t2).s = (1-s)*t1 + s*t2 by A1,Def3
    .= (t2 - t1)*s + t1;
end;
