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)] 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)]