A change from alpha wave drowsiness to lower frequency theta brain waves signify early sleep.

从α波睡意到较低频的脑电波的变化表示早睡。

So this is going to be equal to the sine of theta.

两侧可以同时乘以重力的大小。

This is equal to the sine of theta.

两侧可以同时乘以重力的大小。

There are three frequencies that we need to understand, Beta frequency, Theta frequency, and Alpha frequency.

我们需要解三种频，贝塔频，西塔频和阿尔法频。

And that's why it's cosine of theta.

因此 两者相等。

So the factor by which the slice gets squished down in this direction is exactly cosine of theta.

因此，切片 在这个方向上被压扁的因素正是 theta 的余弦。

So this is 90 minus theta degrees.

这个也是90-θ度。

This too will be 90 minus theta degrees.

再看如何求出这个角。

This right here is 90 minus theta.

那么上面这个角是多少。

And now for the Y direction we can use the definition of sine of theta.

现在对于 Y 方向，我们可以使用正弦函数的定义。

I'm gonna use sine of theta, oh sorry, sine of phi.

我要使用正弦 theta， 哦抱歉，正弦 phi。

And they observed an increase in so-called theta activity.

他们观察到所谓的 theta 活动有所增加。

Remember, the mass ratio of our blocks determines this angle theta in the analogy.

请记住，我们块的质量比决定了类比中的角度 θ。

Let's call the angle between this momentum line and the vertical " theta" .

我们将这条动量线与垂直线之间的角度称为“theta”。

" d" theta, which I like to think of as signaling the fact that some kind of limit is being taken.

“d”theta，我喜欢将其视为表明 正在采取某种限制的事实。

Likelihood of theta given D, or gamma.

给定 D, θ 的概, 或伽马。

So, the cosine of theta is equal to the (ball’s position) divided by its (amplitude).

因此， theta 的余弦等于（球的位置）除以它的（振幅）。

Sine theta equals opposite over hypotenuse.

正弦θ等于对边除以斜边。

But for rotational motion, we really want to know the object’s angle -- what we call theta.

但是对于旋转运动， 我们真的想知道体的角度——我们称之为 theta。

Theta is, how might you proceed?

，您会如何进行？