What does Tan mean in mathematics?

Trigonometric function symbol, which means tangent, is defined as:

In a right triangle, Tana = the length of the opposite side/the length of the adjacent side of a.

The definition of high school mathematics is:

If the coordinate of any point P on the terminal edge of A is (x, y) on the plane rectangular coordinate plane (x is not 0, that is, point P is not on the y axis).

TanA=y/x

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