Создание и использование объектов

Type    FourAngle=class
Xl,yl,x2,y2,x3,y3,x4,y4,
A,B,C,D,D1,D2,
Alpha,Beta,Gamma,Delta,
P,S: real;
Procedure Init;
Procedure Storony;
Procedure Diagonali;
Procedure Angles;
Procedure Perimetr;
Procedure Ploshad;
Procedure PrintElements;
End;
 
Parall=class(FourAngle)
Procedure Storony;
Procedure Perimetr;
Procedure Ploshad;
End;
Romb=class(Parall)
Procedure Storony;
Procedure Perimetr;
End;
Kvadrat=class(Romb)
Procedure Angles;
Procedure Ploshad;
End;
 
Procedure FourAngle.Init;
Begin
Write('Введите координаты вершин заданного четырехугольника:');
ReadLn (xl, yl,x2, y2, x3, y3, x4, y4) ;
End;
Procedure FourAngle.Storony;
Begin
A:=Sqrt(Sqr(x2-xl)+Sqr(y2-yl));
B:=Sqrt(Sqr(x3-x2)+Sqr(y3-y2));
C:=Sqrt(Sqr(x4-x3)+Sqr(y4-y3));
D:=Sqrt(Sqr(x4-xl)+Sqr(y4-yl));
End;
Procedure FourAngle.Diagonali;
Begin
D1:=Sqrt(Sqr(xl-x3)+Sqr(yl-y3));
D2:=Sqrt(Sqr(x2-x4)+Sqr(y2-y4));
End;
Procedure FourAngle.Angles;
Function Ugol(Aa,Bb,Cc: real):real;
Var VspCos, VspSin: real; k:integer;
Begin
VspCos:=(Sqr(Aa)+Sqr(Bb)-Sqr(Cc))/(2*Aa*Bb);
VspSin:=Sqrt(1-Sqr(VspCos));
If Abs(VspCos)>1e-7
Then
Begin
 if VspCos<0 then k:=1 else k:=0;Ugol:=(ArcTan(VspSin/VspCos)
+Pi*k)/Pi*180 
end
Else Ugol:=90
End;
Begin Alpha:=Ugol(D,A,D2); Beta:=Ugol(A,B,D1);
Gamma:=Ugol(B,C,D2); Delta:=Ugol(C,D,D1);
End;
Procedure FourAngle.Perimetr;
Begin P:=A+B+C+D End;
Procedure FourAngle.Ploshad;
Var Per1, Per2: real;
Begin Per1:=(A+D+D2)/2; Per2:=(B+C+D1)/2;
S:=Sqrt(Per1*(Per1-A)*(Per1-D)*(Per1-D2)) +
Sqrt(Per2*(Per2-B)*(Per2-C)*(Per2-D1))
End;
Procedure FourAngle.PrintElements;
Begin
WriteLn(' Стороны: ',a:10:6,b:10:6,c:10:6, D:10:6,' Углы:', Alpha:10:4, Beta:10:4,Gamma:10:4, Delta:10:4,' Периметр:',P:10:6,' Площадь:',S:10:6,' Диагонали:',D1:10:6,D2:10:6)
End;
Procedure Parall.Storony;
Begin A:=Sqrt(Sqr(x2-xl)+Sqr(y2-yl));
B:=Sqrt(Sqr(x3-x2)+Sqr(y3-y2));
C:=A; D:=B
End;
Procedure Parall.Perimetr;
Begin P:=2*(A+B) End;
Procedure Parall.Ploshad;
Var Per: real;
Begin Per:=(A+D+D2)/2;
S:=2*Sqrt(Per*(Per-A)*(Per-D)*(Per-D2))
End;
Procedure Romb.Storony;
Begin
A:=Sqrt(Sqr(x2-xl)+Sqr(y2-yl) ) ;
B:=A; C:=A; D:=A
End;
Procedure Romb.Perimetr;
Begin P:=2*A End;
Procedure Kvadrat.Angles;
Begin Alpha:=90; Beta:=90; Gamma:=90;
Delta:=90;
End;
Procedure Kvadrat.Ploshad;
Begin S:=Sqr(A)
End;
{ Основная программа }
Var obj: Kvadrat;
     Begin
obj:= Kvadrat.Create;
obj.Init;
obj.Storony;
obj.Diagonali;
obj.Angles;
obj.Perimetr;
obj.Ploshad;
obj.PrintElements
End.