Question

7) The value of cos 2pie/15.cos 4pie/15.cos 8pie/15.cos 14pie/15 is
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Answer 1

Answer:

1/16

Step-by-step explanation:

cos 2pie/15.cos 4pie/15.cos 8pie/15.cos 14pie/15

=(Cos24°Sin6°)(Cos12°Cos48°)

=1/4(Sin30° - Sin18°)(Cos60°+Cos36°)

Putting values -

= 1/4( 1/2 - (√5-1)/4)(1/2+(√5+1)/4)

=1/64(3²-(√5)²)

=1/16 =0.0625