实际上，直线的参数方程总是这个样子的。

In fact, parametric equations of lines always look like that.

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那是球体的一个参数方程。

That is a parametric equation for the sphere.

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我们主要还是关注，参数方程的运用，主要是一维的，比如直线、曲线等。

So, we have mostly focused on the use of parametric equations just for one dimensional objects, lines, and curves.

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Now, the most interesting one for our class the equation of state that's the most interesting, is the Van der Waals equation of state, developed by Mr. Van der Waals in 1873.

由范德瓦尔斯在1873年发展起来,这个方程的美妙之处，在于它只需要两个参数，下面我们来研究一下。

麻省理工公开课 - 热力学与动力学课程节选

So prices are determined as follows: prices depend on some parameters I'm just going to call a and b, and let me write the equation and then we'll see what it looks like.

价格由如下因素决定,价格取决于两个参数a和b,我们用方程写一下吧

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