program tamgiac;

uses crt;

var a,b,c,cv:integer;

      P,dt:real;

begin

clrscr;

write('Nhap do dai canh thu nhat: );    readln(a);

write('Nhap do dai canh thu hai: );    readln(b);

write('Nhap do dai canh thu ba: );    readln(c);

cv:=a+b+c;     {cong thuc tinh chu vi}

writeln('Chu vi tam giac la: ',cv);

P:=(a+b+c)/2;     {nua dien tich}

dt:=sqrt(P*(P-a)*(P-b)*(P-c));     {cong thuc tinh dien tich}

writeln('Dien tich tam giac la: ',dt:2:2);

if (a=b) or (b=c) or (a=c) then writeln('Day la tam giac can')

       else writeln('Khong phai tam giac can');

if (a*a+b*b=c*c) or (b*b+c*c=a*a) or (a*a+c*c=b*b) then write('Day la tam giac vuong')

       else write('Khong phai tam giac vuong');

readln

end.

Cho mình ctlhn nha!

Áp dụng hệ thứ hê-rông nhé.

uses crt;
var a,b,c,p:real;
begin
clrscr;
   write('Nhap 3 canh= ');readln(a,b,c);
   writeln('Chu vi: ',a+b+c:0:2);
   p:=(a+b+c)/2;
   writeln('Dien tich: ',sqrt(p*(p-a)*(p-b)*(p-c)));
   if (a=b)or(b=c)or(a=c) then writeln('Day la tam giac can') else
   if (sqr(a)=sqr(b)+sqr(c))or(sqr(b)=sqr(a)+sqr(c))or(sqr(c)=sqr(a)+sqr(b))
   then writeln('Day la tam giac vuong')
   else writeln('Day khong la tam giac can hay tam giac vuong');
readln
end.