1/ program bt;
uses crt;
var r,S,C:real;
begin
clrscr;
writeln('hay nhap ban kinh: ');readln(r);
S:=r*r*pi;
C:=r*2*pi;
writeln('dien tich hinh tron la: ',S);
writeln('chu vi hinh tron la: ',C);
readln;
end.

2/program bt;
uses crt;
var a,b,dt,cv:real;
begin
clrscr;
writeln('hay nhap chieu rong: ');readln(a);
writeln('hay nhap chieu dai: ');readln(b);
dt:=a*b;
cv:=(a+b)*2;
writeln('chu vi hinh chu nhat la: ',cv);
write('dien tich hinh chu nhat la: ',dt);
readln;
end.