每日科技英文19: Trigonometric function

In mathematics, the trigonometric functions(also called circular functions, angle functions or goniometric functions are functions of an angle.

• the trigonometric functions: 三角函数
• circular functions: 圆函数
• goniometric functions: 测角函数
• function of an angle: 角函数

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They relate the angles of a triangle to the lengths of its sides.

重点句型:

• relate A to B: 数学中常用句型，relate为动词，表示 A与B相关 或 A涉及B 或 将A与B联系起来...

• They指代三角函数

• 整句连起来就是:三角函数把三角形的角与它的边的长度联系起来(语文不太好，翻译的比较生硬)

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Trigonometric functions are important in the study of triangles and modeling periodic phenomena, among many other applications.

• be important in... 在...方面很重要
• in the study of trangles: 在三角形的学习方面(be important in)
• in modeling periodic phenomena: 在周期现象建模方面
• and 连词连接的是in后面的内容，介词in表示在...方面。而model做动词，但是前面是介词，所以必须要动名词形式，因此加ing。

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The cosine of an angle is the ratio of the length of the adjacent side to the length of the hypotenuse。

• ratio of sth to sth：昨天的sine中详细讲解了
• the adjacent side: 相邻的边(邻边)
• the hypotenuse: （直角三角形的） 斜边
• 再加一个单词活就齐了: the opposite side 对边

cosine.png sine.png