So, in a way, you can think of these as a space analog of polar coordinates because you just use distance to the origin, and then you have to use angles to determine in which direction you're going.

也可以把这种坐标，看成是空间中的极坐标，它其实使用了，距离原点的距离，然后用角度这种标尺，来确定了方向。

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Often, scientists see large chunks drifting in polar seas, and then have to work backwards to figure out the point of origin.

通常来说，科学家们都是先观测到极地洋面漂浮着大面积冰块，之后再追溯它原始的形成过程。

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We could do it dy dx. Or, maybe we will want to actually make a change of variables to first shift this to the origin, x-2 you know, change x to x minus two and then switch to polar coordinates.

也可以dy，dx来划分，或者,对变量做一下变化，移动到原点，就是把x变成,然后再转化成极坐标。

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