uses crt;

var    a,b,c: real;

        s,p,ha,hb,hc: real;

begin

clrscr;

writeln('Nhap vao day cac canh: ');

write('Canh thu nhat: '); readln(a);

write('Canh thu hai: '); readln(b);

write('Canh thu ba: '); readln(c);

if (a+b > c) and (b+c > a) and (c+a > b) then

   begin

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

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

           writeln('Du dieu kien la tam giac);

          writeln('Dien tich tam giac: ',s ); 

          writeln('Duong cao ung voi canh a: ', 2s/a);

          writeln('Duong cao ung voi canh b: ', 2s/b);

          writeln('Duong cao ung voi canh c: ', 2s/c);

          writeln('Nhan Enter');

end

else writeln('ERROR. Khong phai tam giac');

readln

end.