Trigonometric1.诱导公式sin(-a) = - sin(a) cos(-a) = cos(a)sin(/2 - a) = cos(a)cos(/2 - a) = sin(a)sin(/2 + a) = cos(a)cos(/2 + a) = - sin(a)sin( - a) = sin(a)cos( - a) = - cos(a)sin( + a) = - sin(a)cos( + a) = - cos(a) 2.两角和与差的三角函数 sin(a + b) = sin(a)cos(b) + cos()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)
