令α=(1/2)x + π/6∵-1≤sinα≤1∴当sinα=-1时，f(x)有最大值2此时(1/2)x + π/6=2kπ - π/2(1/2)x=2kπ - 2π/3x=4kπ - 4π/3，k∈Z当sinα=1时，f(x)有最小值-2此时(1/2)x + π/6=2kπ + π/2(1/2)x=2kπ + π/3x=4kπ + 2π/3，k∈Z
