也就是我们在这里得到了单位圆。

So, that means that here, we actually have the unit circle.

youdao

是一个半径为1的圆，那是单位圆。

That is a circle of radius 1. That's the unit circle.

youdao

这就等于一个单位圆的面积。

Well, it's just the area of a unit circle.

youdao

在单位圆上方意味着，我不关心无穷远处。

Above the unit disk means I don't care about this infinite surface.

youdao

它将会是这个单位圆。

It is going to be this unit disk.

youdao

让我们来做第二部分，这是单位圆上的一段圆弧。

Let's do the second part, which is a portion of the unit circle.

youdao

我们在单位圆上。

And we will say, we are on the unit circle.

youdao

我们在单位圆上。

And we will say, we are on the unit circle.

youdao