Question

cos(2π-π/6)的值？

Answer 1

cos(2π-π/6)可以化简为cos(12π/6 - π/6)。
因为cos(a-b) = cos(a)cos(b) + sin(a)sin(b)
所以： cos(12π/6-π/6) = cos(12π/6)cos(π/6) + sin(12π/6)sin(π/6)
因为cos(π/6) = √3/2, sin(π/6) = 1/2，cos(2nπ) = 1，sin(2nπ) = 0
所以： cos(12π/6-π/6) = cos(2π)cos(π/6) + sin(2π)sin(π/6) = 1 * √3/2 + 0 * 1/2 = √3/2
因此，cos(2π-π/6)的值是√3/2。