(PECL imagick 2.0.0)
ImagickDraw::arc — Draws an arc
$sx
   , float $sy
   , float $ex
   , float $ey
   , float $sd
   , float $ed
   )This function is currently not documented; only its argument list is available.
Draws an arc falling within a specified bounding rectangle on the image.
sxStarting x ordinate of bounding rectangle
systarting y ordinate of bounding rectangle
exending x ordinate of bounding rectangle
eyending y ordinate of bounding rectangle
sdstarting degrees of rotation
edending degrees of rotation
No value is returned.
Example #1 ImagickDraw::arc()
<?php
function arc($strokeColor, $fillColor, $backgroundColor, $startX, $startY, $endX, $endY, $startAngle, $endAngle) {
    //Create a ImagickDraw object to draw into.
    $draw = new \ImagickDraw();
    $draw->setStrokeWidth(1);
    $draw->setStrokeColor($strokeColor);
    $draw->setFillColor($fillColor);
    $draw->setStrokeWidth(2);
    $draw->arc($startX, $startY, $endX, $endY, $startAngle, $endAngle);
    //Create an image object which the draw commands can be rendered into
    $image = new \Imagick();
    $image->newImage(IMAGE_WIDTH, IMAGE_HEIGHT, $backgroundColor);
    $image->setImageFormat("png");
    //Render the draw commands in the ImagickDraw object 
    //into the image.
    $image->drawImage($draw);
    //Send the image to the browser
    header("Content-Type: image/png");
    echo $image->getImageBlob();
}
?>