You know, cosine is adjacent over hypotenuse.

你们知道 cos是邻边除以斜边。

That's the cosine of 30 degrees.

这是cos30度。

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。

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

但让我们再来说说正弦、余弦和对数函数。

What's the cosine of 30 degrees?

cos30度是多少？

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何。

98 times the cosine of 30 degrees newtons.

98乘以 cos 30度牛顿。

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

因此 两者相等。

Because cosine of 0 right now is 1.

因此 两者相等。

So this is equal to cosine of the angle.

cosθ等于邻边/斜边。