The value of
sinπ14 sin3π14 sin5π14 sin7π14 sin9π14 sin11π14 sin13π14 is equal to
164
sinπ14 sin3π14 sin5π14 sin7π14 sin9π14 sin11π14 sin13π14
=sinπ14 sin3π14 sin5π14×1×sin(π−5π14) sin(π−3π14) sin(π−π14)
=[sinπ14 sin3π14 sin5π14 sin7π14]2=164