设函数f(θ)=-1/2+(sin5θ/2)/(2sinθ/2),0
问题描述：
设函数f(θ)=-1/2+(sin5θ/2)/(2sinθ/2),0
答
1.f(θ)=-1/2+(sin5θ/2)/(2sinθ/2)=-1/2+[sin(2θ)cos(θ/2)+cos(2θ)sin(θ/2)]/[2sin(θ/2)]=-1/2+cos(2θ)/2+[2sinθcosθcos(θ/2)]/[2sin(θ/2)]=-1/2+cos(2θ)/2+2cosθ[cos(θ/2)]^2=-1/2+[2(cosθ)^2-1]/2...