Circle area

#$usr/bin/perl
use 5.010;
use warnings;
use strict;
use Math::Trig;

#ex1 finding area of a circle
say "Enter the radius";

chomp(my $radius = <STDIN>);

if($radius >= 0 ){

    my $area = pi*2*$radius;
    printf "The area of the circle is: %.2f\n", $area;

}
else{
    say "The area is 0";