Answer
$1$
Work Step by Step
$\sin \dfrac {\pi }{5}\cos \dfrac {3\pi }{10}+\cos \dfrac {\pi }{5}\sin \dfrac {3\pi }{10}=\sin \left( \dfrac {\pi }{5}+\dfrac {3\pi }{10}\right) =\sin \dfrac {\pi }{2}=1$
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