Question #c9b97

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Answer 1 · 2018-02-04T04:34:08

Please refer to the Explanation.

We use the Identity #cos2theta+1=2cos^2theta#.

Now, #(2cos2x+cos^2 2x+1)/4#,

#=1/4{(cos 2x)^2+2*cos2x*1+1^2}#,

#=1/4(cos2x+1)^2#,

#=1/4(2cos^2x)^2#,

#=1/4*4cos^4x#,

#=cos^4x#.