Three different trig ratios, sin, cos, and tan.

三种三角函数，正弦，余弦，正切。

But let me go back to these sines, cosines and logarithms.

让我们再来说说正弦、余弦和对数函数。

I actually write it with these little ridges in it, so SOH... CAH... TOA.

我写的时候会写成这种三角的形状，这是正弦，余弦，正切。

And compute over 10,000 calculations by cosine, square root and lately Analytic Geometry.

还要完成上万笔计算处理余弦，平方根，最近还用起了解析几。

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。

How is knowing cosines gonna help you with your backstroke?

学会余弦对仰泳有什么帮助？

I don't have the slightest idea what sine and cosine mean.

我根本不知道正弦和余弦是什么意思。

Here I'm only showing cosines for simplicity.

在这里， 为了简单起见，我余弦。

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）。

So, the law of cosines is an extension of the pythagorean theorem to the arbitrary angles...

所以余弦定律是勾股定理对任意角度的延伸。

It's all just trigonometry, connecting sides and angles through sines and cosines.

这是三角学，上边 以及跨正弦和余弦的角度。

In other words, the ball’s position is equal to (the amplitude), times (the cosine of the angle).

换句话说， 球的位置等于（振幅）乘以（角度的余弦值）。

In other words, the ball's position is equal to (the amplitude), times (the cosine of the angle).

换句话说，球的位置等于 幅度乘以角度的余弦的乘积。

And then I need to multiply by cosine of the angle in this case the angle is 30 degrees.

然后我需要乘以角度的余弦，在这种情况下角度是 30 度。

So the angle, theta, is 0, and the cosine of 0 is 1.

所以角度、θ、0 和余弦 0 是 1。

Well, it's going to be the tension in the first wire, 200 Newtons times the cosine of 30 degrees.

好吧，这将是第一根电线的张力，200 牛顿乘以 30 度的余弦。

Cos frequency basically means time you repeat something - the amount of times you repeat something in a given amount of time.

余弦频率基本上意味着你重复某事的时间 - 在给定时间内重复某事的次数。

Anything times 1 is equal to itself, so we can just knock the cosine of theta term out of the integral.

乘以任 1 等于它自己，所以我们可以将 theta 范围的余弦乘以积分。

Since the magnetic field is perpendicular to the loop, the cosine of the angle is 1, so that term drops out of the equation.

由于磁场垂直于环，因此角度的余弦为 1，因此该项从方程中消失。

So, for example, I don't think that being a math person means that you can recite the formulas between the sines, cosines, tangents and to use logarithms and exponentials interchangeably.

所以，比如，我认为成为数学家不是指你要能背诵正弦、余弦、正切的函数公式和转化运用对数和指数。