SOLUTION: Show that 2 7 sin4 2𝜃 sin4 𝜃 = cos 12𝜃 − 4 cos 10𝜃 + 2 cos 8𝜃 + 12 cos 6𝜃 − 17 cos 4𝜃 − 8 cos 2𝜃 + 14 Sum the series sin 𝜃 sin 2𝜃 + sin 2�

Question 1182330: Show that
2
7
sin4 2𝜃 sin4 𝜃 = cos 12𝜃 − 4 cos 10𝜃 + 2 cos 8𝜃 + 12 cos 6𝜃 − 17 cos 4𝜃 − 8 cos 2𝜃 + 14
Sum the series
sin 𝜃 sin 2𝜃 + sin 2𝜃 sin 3𝜃 + sin 3𝜃 sin 4𝜃 + ⋯ upto n terms, 𝑛 ∈ ℕ
Solve the equation
(𝑧 + 1)
7 = 𝑧
7
[cos 7𝛼 + 𝑖 sin 7𝛼] .
Answer by ikleyn(52777) (Show Source): You can put this solution on YOUR website!
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