First of all, sinθ is not a fraction. In most cases, it is an infinite acyclic irrational number, and it will be a rational number (fraction) if and only if θ = 30.

Sinθ You can only think of it as a right triangle, the ratio of the opposite side of the acute angle θ to the hypotenuse. The result of this ratio is probably not a fraction, but an irrational number! !

Next comes the second point of your question.

Both a and g are called acceleration, and their properties are the same: physical quantities representing the changing speed of object motion. This physical quantity is a vector.

The so-called vector, with both magnitude and direction, is a vector, such as displacement and force.

There are also physical quantities, such as current, mechanical energy and time, which are called scalars.

Because the vector has a direction, the contrast scalar has a "geometric property"