Let f(x)= log_e ( sin x),(0<x<π) and g(x)= sin^-1( e^-x),(x ≥ 0). If α is a positive real number such that a =(f_° g)^′(α) and b =(f ° g)(α), then:

Let $\displaystyle f(x)=\log _{\mathrm{e}}(\sin x),(0<x<\pi)$ and $\displaystyle g(x)=\sin ^{-1}\left(\mathrm{e}^{-x}\right),(x \geqslant 0)$. If $\displaystyle \alpha$ is a positive real number such that $\displaystyle \mathrm{a}=\left(f_{\circ} g\right)^{\prime}(\alpha)$ and $\displaystyle \mathrm{b}=(f \circ g)(\alpha)$, then :