The value of cos ⁡ π 2 2 ⋅ cos ⁡ π 2 3 ⋅ … ⋅ cos ⁡ &#960…

The value of cosπ22cosπ23cosπ210sinπ210 is:
  1. 11024
  2. 1512
  3. 12
  4. 1256

Solution

Given cosπ22·cosπ23·...·cosπ210·sinπ210

=sin29.π21029.sinπ210.sinπ210

Using  cosA.cos2A.cos22A.cos23A.cos24A.....cos2n-1A=sin2nA2nsinA

=129

=1512

Asked in: JEE Main 2019 (10 Jan Shift 2)

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