国际课程提前学,A-Level数学之三角函数2:基础三角函数

三角函数

 

 

Sin 正弦,cos 余弦,tan 正切,是三个最常用的三角函数。

 

The simplest definitions of the trigonometrical functions are given in terms of the ratios of the sides of a right-angled triangle, for values of the angle θ between 0° and 90°.

首先,通过直角三角形,在0到90度范围内来讨论最基础的三角函数。

 

 

Example1

 

 

Evaluating Trigonometric Functions

 

Use the triangle to find the values of .

 

Solution:

By the Pythagorean Theorem,

(hyp)2 = (opp)2 + (adj)2, it follows that

 

 

Example2

 

 

Find the three trigonometric ratios  of  the angles 30°and 60°

 

 

 

Exercise1

 

 

Find the three trigonometric ratios of the angle 45°

 

The triangle PQR is a right-angled isosceles triangle with equal sides of length 1 unit.

 

 

 

Trigonometric function of special angles

特殊角的三角函数值

 

 

 

 

更多Alevel课程
翰林国际教育资讯二维码