HTML5 Canvas 绘制五角星

代码：
<!DOCTYPE html>
<html lang="utf-8">
<meta http-equiv="Content-Type" content="text/html; charset=utf-8"/>
<head>
     <title>五角星</title>
    </head>

     <body onload="draw()">
        <canvas id="myCanvus" width="200px" height="200px" style="border:0px dashed black;">
            出现文字表示你的浏览器不支持HTML5
        </canvas>
     </body>
</html>
<script type="text/javascript">
<!--
    function draw(){
        var canvas=document.getElementById("myCanvus");
        var context=canvas.getContext("2d");

        context.fillStyle = "yellow";
        context.fillRect(0, 0, 200, 200);

        context.strokeStyle = "rgb(250,0,0)";
        context.fillStyle = "rgb(250,0,0)"

        context.beginPath();
        context.moveTo(100, 0);
        context.lineTo(100+Math.cos(Math.PI*3/10)*100, 100+Math.sin(Math.PI*3/10)*100);
        context.lineTo(100-Math.cos(Math.PI*1/10)*100, 100-Math.sin(Math.PI*1/10)*100);
        context.lineTo(100+Math.cos(Math.PI*1/10)*100, 100-Math.sin(Math.PI*1/10)*100);
        context.lineTo(100-Math.cos(Math.PI*3/10)*100, 100+Math.sin(Math.PI*3/10)*100);
        context.lineTo(100, 0);
        context.fill();
        context.stroke();
        context.closePath();
    }
//-->
</script>