var a,b,c,p,s: real;
begin
writeln('NHAP BA CANH TAM GIAC: ');
repeat
write('a = '); readln(a);
write('b = '); readln(b);
write('c = '); readln(c);
until (a+b>c) and (b+c>a) and (c+a>b);
p:=(a+b+c)/2;
s:=sqrt(p*(p-a)*(p-b)*(p-c));
writeln('Chu vi tam giac: ',2*p:5:2);
writeln('Dien tich tam giac: ',s:5:2);
writeln('Ban kinh duong tron ngoai tiep: ',a*b*c/(4*s):5:2);
writeln('Ban kinh duong tron noi tiep: ',s/p:5:2);
end.