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virtus
 2 years ago
Show that cos(4)x =8(cos^(4)x cos^(2)x)+1
virtus
 2 years ago
Show that cos(4)x =8(cos^(4)x cos^(2)x)+1

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ganeshie8
 2 years ago
Best ResponseYou've already chosen the best response.0start by factoring out cos^2 from first two terms

ganeshie8
 2 years ago
Best ResponseYou've already chosen the best response.0\(\huge 8(cos^4x cos^2x) + 1\) is this the RHS ?

y2o2
 2 years ago
Best ResponseYou've already chosen the best response.3\[\large L.H.S = [ 8\cos^ 2(x)(\cos^2(x)  1) ]+1 = [ 8\cos^ 2(x)\sin^2(x) ]+1 \] \[\large = [ 2 (2\sin(x)\cos(x))^2 ]+1 = [2(\sin(2x) ) ^2 ] + 1 \] \[\large = 12\sin^2(2x) = \cos^2(2x)  \sin^2(2x) = \cos(4x) = R.H.S\]

virtus
 2 years ago
Best ResponseYou've already chosen the best response.0thanks guys, i will look at this later because i am super sleepy
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