cho mk xin ctrlhn nha, chứ cái này hơi dài đấy

đây nha, chúc bạn học tốt!

uses crt;

var n,t: array[1..100] of integer;

i:integer;

a,b,h1,c,h2,d,e,s1,s2,s3: real;

key:char;

procedure hinh_chu_nhat;

begin

repeat

clrscr;

writeln('DIEN TICH HINH CHU NHAT');

writeln('---------------------------------');

writeln;

write('nhap chieu dai: ');readln(a);

write('nhap chieu rong: ');readln(b);

s1:=a*b;

writeln('dien tich hinh chu nhat la: ',s1:6:3);

write('nhan "0" de thoat');

key:=readkey;

until key = '0';

end;

procedure hinh_thang;

begin

repeat

clrscr;

writeln('DIEN TICH HINH THANG');

writeln('-----------------------------');

writeln;

write('nhap do dai day lon: '); readln(c);

write('nhap do dai day be: '); readln(d);

write('nhap chieu cao: '); readln(h1);

s2:= (c+d)*h1/2;

writeln('dien tich hinh thang la: ',s2:6:3);

write('nhan "0" de thoat');

key:=readkey;

until key='0';

end;

procedure hinh_tam_giac;

begin

repeat

clrscr;

writeln('DIEN TICH HINH TAM GIAC');

writeln('--------------------------------');

writeln;

write('nhap do dai canh day: '); readln(e);

write('nhap chieu cao: '); readln(h2);

s3:= 1/2*e*h2;

writeln('dien tich tam giac la: ',s3:6:3);

write('nhan "0" de thoat');

key:=readkey;

until key='0';

end;

procedure trang_chu;

begin

for i:=1 to 100 do

begin

n[i]:=0;

t[i]:=0;

end;

clrscr;

writeln('1: dien tich hinh chu nhat');

writeln('2: dien tich hinh thang');

writeln('3: dien tich hinh tam giac');

writeln('0: thoat chuong trinh');

writeln;

write('nhap ma so: '); key:=readkey;

case key of

'1':hinh_chu_nhat;

'2':hinh_thang;

'3':hinh_tam_giac;

'0':exit;

else

begin

writeln('khong ton tai');

delay(1000);

end;

end;

trang_chu;

end;

begin

clrscr;

trang_chu;

end.