Question

Prove that cosπ/9 cos2π/9 cos4π/9 = 1/16
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Answer 1

Step-by-step explanation:

=sin(π/9)*cos(π/9)*cos(2π/9)*cos(3π/9)*cos(4π/9)/sin(π/9)

=sin(2π/9)cos(2π/9)*cos(3π/9)*cos(4π/9)/[2*sin(π/9)]

=sin(4π/9)*cos(3π/9)*cos(4π/9)/[4*sin(π/9)]

=sin(8π/9)*cos(3π/9)/[8*sin(π/9)]

=sin(π/9)*cos(3π/9)/[8*sin(π/9)]

=cos(3π/9)/8

=1/16

YOU CAN SEE PICTURE FOR REFERENCE.

HOPE IT HELPS!