asked 85.6k views
1 vote
Find an identity for cos(4t) in terms of cos(t)cos⁡(t).

1 Answer

5 votes

\cos4t=2\cos^22t-1=2(2\cos^2t-1)^2-1

\cos4t=8\cos^4t-8\cos^2t+1
answered
User Firzok Nadeem
by
8.4k points
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