freepascal.compiler/docs/refex/ex12.pp

Program Example12;

{ Program to demonstrate the Cos function. }

Var R : Real;

begin
  R:=Cos(Pi);    { R:=-1 }
  R:=Cos(Pi/2);  { R:=0  }
  R:=Cos(0);     { R:=1  }    
end.