카타 8급 Area of a Square

PHP

function square_area($A) {
  return round(pow($A*2/M_PI,2), 2);
}

function square_area($A) {
  $r = 2*$A/M_PI;
  return round($r*$r,2);
}

function square_area($A) {
  $r = 2*$A/pi();
  return round($r**2,2);
}