首先b=a—8/3π,f(x)=(1+cosa)/(1/sin(a/2)—sin(a/2))-4sin²(a/4+π/12)
=2cos²(a/2)sin(a/2)/(1-sin²(a/2))-2+2cos(a/2+π/6)
=sina/2﹣2+√3 cosa/2
=2sin(a/2+π/3)-2
∴最大值是0
最大值的条件:a=4kπ-π/3(k∈Z)
首先b=a—8/3π,f(x)=(1+cosa)/(1/sin(a/2)—sin(a/2))-4sin²(a/4+π/12)
=2cos²(a/2)sin(a/2)/(1-sin²(a/2))-2+2cos(a/2+π/6)
=sina/2﹣2+√3 cosa/2
=2sin(a/2+π/3)-2
∴最大值是0
最大值的条件:a=4kπ-π/3(k∈Z)