$\underline{\text{1.}}$

uses crt;
var cd,cr,cv,dt:integer;
begin
    clrscr;
    readln(cd,cr);
    cv:=(cd+cr)*2;
    dt:=cd*cr;
    writeln('chu vi: ',cv);
    writeln('dien tich: ',dt);
    readln;
end.

$\\$

$\underline{\text{2.}}$

uses crt;
var c,cv,dt:integer;
begin
    clrscr;
    readln(c);
    cv:=c*4;
    dt:=c*c;
    writeln('chu vi: ',cv);
    writeln('dien tich: ',dt);
    readln;
end.

$\\$

$\underline{\text{3.}}$

uses crt;
var bk,dk:integer; cv,dt:real;
begin
    clrscr;
    readln(bk);
    cv:=bk*2*3.14;
    dt:=bk*bk*3.14;
    dk:=bk*2;
    writeln('chu vi: ',cv:4:2);
    writeln('dien tich: ',dt:4:2);
    writeln('duong kinh: ',dk);
    readln;
end.

`@Daoanhviet96`

1.

uses crt;
var a,b:integer;
begin
clrscr;
write('Nhap chieu dai: '); readln(a);
write('Nhap chieu rong: '); readln(b);
writeln('Chu vi hinh chu nhat la: ',(a+b)*2);
writeln('Dien tich hinh chu nhat la: ',a*b);
readln
end.

2.

uses crt;
var a:integer;
begin
clrscr;
write('Nhap canh hinh vuong: '); readln(a);
writeln('Chu vi hinh vuong la: ',a*4);
writeln('Dien tich hinh vuong la: ',a*a);
readln
end.

3. 

uses crt;
var a:integer;
chuvi,dientich:real;
begin
clrscr;
write('Nhap ban kinh hinh tron: '); readln(a);
chuvi:=a*2*3.14;
writeln('Chu vi hinh tron la: ',chuvi:0:2);
dientich:=a*a*3.14;
writeln('Dien tich hinh tron la: ',dientich:0:2);
write('Duong kinh hinh tron la: ',a*2);
readln
end.