Program hoc24;
Uses crt;
Var r,S,C:real;
Begin
Write ('Ban kinh la');
Readln (r);
S:=r*r*3.14;
C:=r*2*3.14;
Writeln ('Chu vi la',C);
Writeln ('Dien tich la',S);
Readln;
End.
uses crt;
var r,cv,dt:real;
begin
clrscr;
repeat
write('Nhap ban kinh:');readln(r);
until r>0;
cv:=r*2*pi;
dt:=sqr(r)*pi;
writeln('Chu vi=',cv:4:2);
writeln('Dien tich=',dt:4:2);
readln;
end.