4)var a,b,p:real;
begin
Write('Введите a >>> ');
Read(a);
Write('Введите b >>>');
Read(b);
p:=a+b+Sqrt(a*a+b*b);
Writeln('===================');
Write('Периметр >>> ');
end.
5)var r1,r2,s:real;
begin
Write('Введите r1 >>> ');
Read(r1);
Write('Введите r2 >>> ');
Read(r2);
Writeln('===================');
s:=(Pi*r1*r1)-(Pi*r2*r2);
Write('Площадь >>> ',s);
end.
6)var x,y,s:real;
begin
Write('Введите x >>> ');
Read(x);
Write('Введите y >>> ');
Read(y);
Writeln('===================');
s:=(2*x+y)*(x-y);
Write('s >>> ',s);
end.