反过来，有一个关于x和y的函数,也可以表示成极坐标r和θ

Or, the other way around, I have a function of x and y and I want to express it in terms of the polar coordinates r and theta.

youdao

把一个函数，在直角坐标和极坐标中转换。

You have a function that you want to switch between rectangular and polar coordinates.

youdao

比如说极坐标，有一个函数,是根据极坐标θ定义的。

Say, polar coordinates. Let's say that I have a function but is defined in terms of the polar coordinate variables on theta.

youdao