Hình vuông

Program dien_tich;
Uses crt;
Var a, dt, cv : integer;
Begin
Clrscr;
Write('Nhap do dai canh hinh vuong :');readln(a);
cv := a*4;
dt := a*a;
Writeln('Chu vi hinh vuong  la :', cv);
Writeln('Dien tich hinh vuong  la :', dt);
Readln
End.

Hình chữ nhật

Program dien_tich;
Uses crt;
Var a, b, S, cv : real;
Begin
Clrscr;
Write('Nhap do dai canh a :');readln(a);
Write('Nhap do dai canh b :');readln(b);
cv := (a+b)*2;
S := a*b;
Writeln('Chu vi hinh chu nhat  la :', cv:8:2);
Writeln('Dien tich hinh chu nhat  la :', S:8:2);
Readln
End.

Hình tròn

Program Hinh_tron;
Uses crt;
Var r, cv, dt : real;
Begin
Clrscr;
Write ('Nhap ban kinh hinh tron: ');
Readln (r);
cv := 2*pi*r;
dt := r*r*pi;
Writeln('Chu vi hinh tron la : ', cv);
Writeln('Dien tich hinh tron la :', dt);
Readln
End.

Hình tam giác

program tam_giac;
uses crt;
var a, b, c, cv, s, p : real;
begin
clrscr;
write('nhap do dai canh a :');readln(a);
write('nhap do dai canh b :');readln(b);
write('nhap do dai canh c :');readln(c);
cv := a+b+c;
p := cv/2;
s := sqrt(p*(p-a)*(p-c)*(p-b));
writeln('chu vi hinh tam giac la :', cv:8:2);
writeln('dien tich hinh tam giac la :', s:8:2);
readln
end.