reserve f,f1,f2,g for PartFunc of REAL,REAL;
reserve A for non empty closed_interval Subset of REAL;
reserve p,r,x,x0 for Real;
reserve n for Element of NAT;
reserve Z for open Subset of REAL;

theorem Th29:
  (-cos)`|REAL = sin by Th26,FDIFF_1:def 7,SIN_COS:24;
