Question

三角函数的计算公式是什么啊？我忘记了。。

Answer 1

sin(-a) = - sin(a)
cos(-a) = cos(a)
sin(π/2 - a) = cos(a)
cos(π/2 - a) = sin(a)
sin(π/2 + a) = cos(a)
cos(π/2 + a) = - sin(a)
sin(π - a) = sin(a)
cos(π - a) = - cos(a)
sin(π + a) = - sin(a)
cos(π + a) = - cos(a)

2.两角和与差的三角函数

sin(a + b) = sin(a)cos(b) + cos(α)sin(b)
cos(a + b) = cos(a)cos(b) - sin(a)sin(b)
sin(a - b) = sin(a)cos(b) - cos(a)sin(b)
cos(a - b) = cos(a)cos(b) + sin(a)sin(b)
tan(a + b) = [tan(a) + tan(b)] / [1 - tan(a)tan(b)]
tan(a - b) = [tan(a) - tan(b)] / [1 + tan(a)tan(b)]

Answer 2

楼上的很全了
补充 tan(-x)= -tan(x)
sin^+cos^=1 (我们老师叫龟形图 包括好几个 都是与1有关的 自己看各种材料都能找到)

Answer 3

http://wenku.baidu.com/view/34d502020740be1e650e9ad1.html.自己看吧，太多了，不好打。

Answer 4

有正弦和余弦之分~