当您需要设置需要直接坐标的标签或箭头时，此操作会非常有用。

This is useful when you need to set a label or an arrow which need explicit coordinates.

youdao

使用这些像素坐标，我们可以绘制以这些点为起点的直线，重新设定直线的颜色、连接直线、用颜色填充周围的区域或者 GD 可以执行的任何其他操作。

With these pixel coordinates, we can draw lines emanating from the the points, recolor them, connect them, fill the surrounding area with color, or anything else GD can do.

youdao

在用这些工具进行绘图时，通过鼠标操作自动设置坐标点和工具类型(比如方框)，并通过GUI环境选择画笔和笔画宽度。

In drawing with those tools, the mouse automatically sets the coordinate points and the type of tool, such as a box, and selects the pen and stroke for you via a GUI environment.

youdao

And so I'm going to go back to this idea of a class, and let's build the first of these, and that is shown right here on this piece of your handout.

你把半径加到一起,你不会把角度加到一起，你需要再笛卡尔坐标下，进行这个操作,那么我这里在讲的就是。

麻省理工公开课 - 计算机科学及编程导论课程节选

And then I could do things like again, say, okay having done, that let me just run it here, run that, so I've now got polar point 1, and polar point 2.

然后给它们赋值半径和角度，然后我可以进行刚才的操作，也就是说，对刚才的笛卡尔坐标进行的操作，让我们来运行下它吧，运行下，现在我有一个极坐标点。

麻省理工公开课 - 计算机科学及编程导论课程节选

It says if I want to get the length of a segment, going to pass in that instance, it says from that instance, get the start point, that's the thing I just found.

它的意思是如果我想要,得到一个线段的长度，首先要把这个实例传进来，然后对于这个实例，从开始点，取得x坐标，然后通过同样的操作。

麻省理工公开课 - 计算机科学及编程导论课程节选