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

但让我们再来说说正弦、弦和对数函数。

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

我写时候会写成种三角形状，正弦，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弦，平方根，最近还用起了解析几何。

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

因此，切 个方向上被扁因素正 theta 弦。

And the cosine of 90 degrees is zero.

90 度弦为零。

The cosine of zero is 1.

零弦 1。

How is knowing cosines gonna help you with your backstroke?

学会弦对仰泳有什么帮助？

However, let's use E dA cosine theta instead of the dot product.

但，让我们使用 E dA 弦西塔来代替点积。

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

我根本不知道正弦和弦什么意思。

As the value t increases, the inside of this cosine function increases more slowly.

随着 t 值增加，该弦函数内部增加得更慢。

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

三角学，上边 以及跨正弦和弦角度。

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

因此， theta 弦等于（球位置）除以它（振幅）。

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

所以弦定律勾股定理对任意角度延伸。

To calculate a triangle's shading, we take the  cosine of the angle or theta between the two directions.

为了计算三角形阴影，我们取两个方向之间角度或 θ 弦。

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弦，种情况下角度 30 度。

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

换句话说， 球位置等于（振幅）乘以（角度弦值）。

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

好吧，将第一根电线张力，200 牛顿乘以 30 度弦。

Then the real part of the sum is the cosine amplitude and the imaginary part is the sine amplitude.

那么总和实部弦振幅，虚部正弦振幅。

The  force of gravity perpendicular equals mass times gravitational field strength times the cosine of  the incline angle.

垂直重力等于质量乘以重力场强度乘以倾斜角弦。

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

因此，切个方向上被扁因素正 theta 弦。