1、f(x) = 1/2 sin2x sinφ + (1+cos2x)/2 cosφ - 1/2 cosφ
= 1/2 sin2x sinφ + 1/2 cos2x cosφ = 1/2 cos(2x-φ)
f(π/6) = 1/2
cos(π/3 - φ) = 1又（0＜φ＜π）
所以φ = π//3
2、g(x)=1/2cos(4x-π/3)
当4x-π/3=0即x=π/12时取最大值1/2
当x=π/4时取最小值-1/4