The sum of the series \cos x-\frac{1}{2} \cos ^2 x+\frac{1}{3} \cos ^3 x-\frac{1}{4} \cos ^4 x+. . . is equal to

Correct Answer is : log2+2log|cos(x2)|

\log 2+2 \log {| \cos (\frac{x}{2}) |}

\log 2-2 \log {| \cos (\frac{x}{2}) |}

\log 2+\log {| \cos (\frac{x}{2}) |}

\log 2-\log {| \cos (\frac{x}{2}) |}

CUSAT 2021 BTech Solved Paper Shift 2

Question : 170 of 250

Marks: +1, -0

The sum of the series cos‌x−‌

cos2x+‌

cos3x−‌

cos4x+... is equal to

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