Bài 3:

program cv_dt_htron;

uses crt;

var s, cv, r: real;

begin

 clrscr;

writeln(‘Nhap chieu dai ban kinh r: ‘); readln(r);

cv:=2*r*pi;

s:=r*r*pi;

writeln(‘Chu vi hinh tron la: ‘, cv);

writeln(‘Dien tich hinh tron la: ‘, s);

readln

Bài 4:

uses crt;

var a,cv,dt:integer;

begin

clrscr;

write('a='); readln(a);

cv:=a*4;

dt:=sqr(a);

if a>0 then

begin

writeln('chu vi hinh vuong la: ',cv);

writeln('dien tich hinh vuong la: ',dt);

end

else writeln('vui long nhap so a lon hon 0');

readln;

end.

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Xin 5* và hay nhất

program bai_3;

uses rt;

var r:real;

const pi=3.14;

begin

clrscr;

write('nhap ban kinh: ');readln(r);

writeln('chu vi la: ',2*r*pi);

writeln('dien tich la: ',r*r*pi);

raedln;

end.

program bai_4;

uses crt; 

var a:rael;

begin

clrscr;

write('nhap canh a: ');readln(a);

writeln('chu vi: ',a*4);

writeln('dien tich: ',a*a);

readln;

end.