cosπ/5cos2π/5=?

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cosπ/5cos2π/5=?cosπ/5cos2π/5=?cosπ/5cos2π/5=?cosπ/5cos2π/5=sinπ/5cosπ/5cos2π/5/sinπ/5=4sinπ/5cosπ/5c

cosπ/5cos2π/5=?
cosπ/5cos2π/5=?

cosπ/5cos2π/5=?
cosπ/5cos2π/5
=sinπ/5cosπ/5cos2π/5/sinπ/5
=4sinπ/5cosπ/5cos2π/5/4sinπ/5
=2sin2π/5cos2π/5/4sinπ/5
=sin4π/5/4sinπ/5
=sin(π-π/5)/4sinπ/5
=(1/4)sinπ/5/sinπ/5
=1/4