Chương trình 1 :

program tam_giac;
uses crt;
var a, b, c, p, s : 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);

p :=(a + b+ c)/2;

s := sqrt(p*(p-a)*(p-b)*(p-c));

Writeln('dien tich tam giac la :', s:8:2);

readln

end.

Chương trình 2 :

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.

*Diện tích tam giác

Program baitap;

Uses crt;

Var a,h:real;

Begin

Clrscr;

Write('Nhap do dai 1 canh'); Readln(a);

Write('Nhap chieu cao tuong ung:'); Readln(h);

Writeln('Dien tich tam giac:', a*h/2:9:3);

Readln

End.

*Chu vi, diện tích hình chữ nhật:

Program baitap;

Uses crt;

Var a,b:real;

Begin

Clrscr;

Write('Nhap chieu dai va chieu rong:');Readln(a,b);

Writeln('Chu vi HCN:',2*(a+b));

Writeln('Dien tich HCN:',a*b);

Readln

End.