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# What is 三角比?

三角比?聽聞中ニ學。About what?

請不要在維基抄一大段文字！

用英文一個一個解答！希望參考您們的課本！

### 1 Answer

- 琴生Lv 51 decade agoFavorite Answer
For a right-angled triangle,

choose an angle instead of the right angle.

The longest side is called hypotenuse.

The angle besides the hypotenuse, which is "connected" to the angle chosen, (also connect to the right angle) is called the adjacent side.

The remaining side is called the opposite side (as it is opposite to the angle chosen).

After understanding the basic definitions before,

let's discuss about the trigonometric ratios.

There are 3 kinds of trigonometric ratios:

sine, cosine and tangent (or sin, cos, tan in short form)

which are respectively defined as follows:

sin = the ratio of opposite side to hypotenuse, i.e. in fraction, (opposite side) / hypotenuse

cos = the ratio of adjacent side to hypotenuse, i.e. in fraction, (adjacent side) / hypotenuse

tan = the ratio of opposite side to adjacent side, i.e. in fraction, (opposite side) / (adjacent side)

Here is the basic definitions of the trigonometric ratios.

2007-01-15 21:09:58 補充：

Sorry for not providing the related picture here and you can try to draw it yourself.

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