MathematicsMedium63×since 2002Q3713If y(θ)=2cosθ+cos2θcos3θ+4cos2θ+5cosθ+2y(\theta)=\frac{2 \cos \theta+\cos 2 \theta}{\cos 3 \theta+4 \cos 2 \theta+5 \cos \theta+2}y(θ)=cos3θ+4cos2θ+5cosθ+22cosθ+cos2θ, then at θ=π2,y′′+y′+y\theta=\frac{\pi}{2}, y^{\prime \prime}+y^{\prime}+yθ=2π,y′′+y′+y is equal to :A12\frac{1}{2}21B1C32\frac{3}{2}23D2Check answerSkip