Uses crt;
Var a, b, c, s, p: real;
Begin
Clrscr;
Write('Nhap 3 canh a, b, c: '); readln(a, b, c);
If ((a + b) > c) and ((b + c) > a) and ((a + c) > b) then 
Begin 
    p:=(a+b+c)/2;
    s:=sqrt(p*(p-a)*(p-b)*(p-c));
End;
Writeln('Chu vi la: ',p:4:2);
Writeln('Dien tich la: ',s:4:2);
Readln
End.

uses crt;

var a, b, c, p, s, cv : real;

begin

clrscr;

write('Nhap ba so a, b, c : '); readln(a, b, c);

if (a > 0) and (b > 0) and (c > 0) then

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

        begin

            writeln('Ba canh la do dai tam giac');

            cv := a + b + c;

            p := (a + b + c) / 2;

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

            writeln('Chu vi : ', cv : 2 : 1);

            writeln('Dien tich : ', s : 2 : 1);

        end

    else writeln('Ba so khong la do dai tam giac')

else writeln('Ba so khong la do dai tam giac');

readln

end.