- #1
banfill_89
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Homework Statement
prove that cos^4(x)= 3/8 +1/2(cos2x)+1/8(cos4x)
Homework Equations
The Attempt at a Solution
i attempted to change the cos2x to 2cos^2(x)-1...then made all them over 8...and now I am stuck...another question...if i multiply 2cos(4x) by 2, do i multiply the 2 and the 4x? or just he 4x?