10.
已知\(α∈(0, \dfrac {π}{2})\),且\(f(a)=\cos α\cdot \sqrt { \dfrac {1-\sin α}{1+\sin \alpha }}+\sin α\cdot \sqrt { \dfrac {1-\cos α}{1+\cos \alpha }}\).
\((1)\)化简\(f(a)\);
\((2)\)若\(f(a)= \dfrac {3}{5}\),求\( \dfrac {\sin α}{1+\cos \alpha }+ \dfrac {\cos α}{1+\sin \alpha }\)的值.