It is the corresponding fraction.
this is found by multipling the denominator of one ratio by the numerator of the other ratio
The numerator of the second ratio and the denominator of the first ratio are called the means, and the numerator of the first ratio and the denominator of the second ratio are called the extremes. The product of the means equals the product of the extremes.
You divide the numerator by the denominator.
You divide the numerator of the ratio by its denominator.
numerator
And the denominator is 0
They are a common factor and any common factor in the numerator and denominator of a ratio can be cancelled out.
If the numerator is 0 AND the denominator is not 0, then the ratio is 0. And cosine of 0 is 1.
It is a ratio.
Dividing the numerator and denominator by a common factor is how you simplify a fraction.
cross product
It is simplifying the ratio.