unit Areas;

(*****************************************************************)

(*                                                               *)

(* This unit includes a collection of functions to calculate the *)

(* areas of four different geometric shapes.                     *)

(*                                                               *)

(*****************************************************************)

interface

   function Area_Of_Circle(Radius : real ) : real;

   function Area_Of_Square(Length_Of_Side : real) : real;

   function Area_Of_Rectangle(Length,Width : real) : real;

   function Area_Of_Triangle(Base, Height : real) : real;
implementation
var My_Pi : real;
procedure Mult_Two_Numbers(Number1, Number2 : real;

                           var Result : real);

begin

   Result := Number1 * Number2;

end;
function Area_Of_Circle;

var Rad_Squared : real;

begin

   Mult_Two_Numbers(Radius,Radius,Rad_Squared);

   Area_Of_Circle := Rad_Squared * My_Pi;

end;
function Area_Of_Square;

begin

   Area_Of_Square := Length_Of_Side * Length_Of_Side;

end;
function Area_Of_Rectangle;

begin

   Area_Of_Rectangle := Length * Width;

end;
function Area_Of_Triangle;

begin

   Area_Of_Triangle := Base * Height / 2.0;

end;
begin                   (* This is the initialization code *)

   My_Pi := 3.14159267;

end.  (* of unit Areas *)


Result of execution

(A unit cannot be executed)