program text;
uses crt;
var i:integer;
    a,b,c,ha,hb,hc,p,S:real;
    X,Y:array[1..3] of integer;
Begin
   clrscr;
   Writeln('Nhap toa do cac dinh A, B, C:');
   for i:= 1 to 3 do readln(X[i],Y[i]);
   a:=sqrt(sqr(X[2]-X[3])+sqr(Y[2]-Y[3]));
   b:=sqrt(sqr(X[1]-X[3])+sqr(Y[1]-Y[3]));
   c:=sqrt(sqr(X[2]-X[1])+sqr(Y[2]-Y[1]));
   p:= (a+b+c)/2;
   S:= sqrt(p*(p-a)*(p-b)*(p-c));
   Writeln('Dien tich cua tam giac la: ',S:0:4);
   ha:=2*S/a;
   hb:=2*S/b;
   hc:=2*S/c;
   writeln('ha = ',ha:0:2,' hb = ',hb:0:2,' hc = ',hc:0:2);
   readln;
end.

uses crt;

var xa,ya,xb,yb,xc,yc,p,s,ab,bc,ac:real;

begin

clrscr;

readln(xa,ya,xb,yb,xc,yc);

ab:=sqrt(sqr(xa-xb)+sqr(ya-yb));

ac:=sqrt(sqr(xa-xc)+sqr(ya-yc));

bc:=sqrt(sqr(xb-xc)+sqr(yb-yc));

p:=(ab+bc+ac)/2;

s:=sqrt(p*(p-ab)*(p-ac)*(p-bc));

writeln(s:4:2);

readln;

end.

Thế còn í b ạ

uses crt;

var i,n:integer;

s:real;

begin

clrscr;

n:=1;

s:=0;

while (n<=10000) do 

begin

n:=n+2;

s:=s+1/n;

end;

writeln(s:4:2);

readln;

end.

Chưa đưa ra kết quả được ạ :<

const fi='songuyen.inp';

fo='tong.out';

var f1,f2:text;

a:array[1..100]of integer;

n,i,dem:integer;

begin

assign(f1,fi); reset(f1);

assign(f2,fo); rewrite(f2);

n:=0;

while not eof(f1) do 

  begin

n:=n+1;

read(f1,a[n]);

end;

dem:=0;

for i:=1 to n do 

  if a[i] mod 2=0 then inc(dem);

writeln(f2,dem);

close(f1);

close(f2);

end.

uses crt;

var st:string;

i,d,dem:integer;

begin

clrscr;

write('Nhap xau:'); readln(st);

d:=length(st);

dem:=0;

for i:=1 to d do 

  if st[i]=#32 then inc(dem);

writeln(dem);

readln;

end.

program dung;

uses crt;

var x: integer'

t: real;

begin

clrscr;

write('x= '); readln(x);

t:=(5*x-7)+sqrt(3*x*x+7*x-6);

write('Dien tich la: ',s:1:2);

write('Ket qua: ',t);

readln;

end.

Câu 3: 

const pi=3.14

var x,y:real;