reserve x,y,t for Real;

theorem Th32:
  -1<t & t<1 implies 0<(t+1)/(1-t)
proof
  assume -1<t & t<1;
  then -1+1<t+1 & t-t<1-t by XREAL_1:8;
  then 0/(1-t)<(t+1)/(1-t);
  hence thesis;
end;
