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If ππ∫02πcos2x dx=k∫0π2cos2x dx, then the value of k is ______. - Mathematics

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Question

If `int_0^(2π) cos^2 x  dx = k int_0^(π/2) cos^2 x  dx`, then the value of k is ______.

Options

  • 4

  • 2

  • 1

  • 0

MCQ
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Solution

If `int_0^(2π) cos^2 x  dx = k int_0^(π/2) cos^2 x  dx`, then the value of k is 4.

Explanation:

`int_0^(2π) cos^2 x  dx = k int_0^(π/2) cos^2 x  dx`

Taking LHS = `int_0^(2π) cos^2 x  dx`

= `2int_0^π cos^2 x  dx` ...[∵ cos2 x is an even function]

= `2 xx 2int_0^(π/2) cos^2 x  dx`  ...[∵ cos2 x is an even function]

= `4int_0^(π/2) cos^2 x  dx`  

On comparing both sides, we get

k = 4.

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