artisan.js如何画三角形

1 artisan.drawLine('canvas',200,200,300,300,1,'red');

  artisan.drawLine('canvas',300,300,250,280,1,'red');

  artisan.drawLine('canvas',250,280,200,200,1,'red');

2

artisan.drawLine('canvas',200,200,300,300,1,'red');

artisan.drawLine('canvas',300,300,250,280,1,'red');

//artisan.drawLine('canvas',250,280,200,200,1,'red');

artisan.closePath('canvas');

为何第二种方法不行呢？