(a) Let $I = \int_{0}^{\frac{\pi}{2}}\frac{\cos x}{1 + \sin x}\ dx$ $= \left\lbrack \log\left( 1 + \sin x \right) \right\rbrack_{0}^{\frac{\pi}{2}}$ $= \log 2 - \log 1 = \log 2$
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