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The maximum value of Δ = |11111+sinθ11+cosθ11| is ______. (θ is real number) - Mathematics

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Question

The maximum value of Δ = `|(1, 1, 1),(1, 1 + sin theta, 1),(1 + cos theta, 1, 1)|` is ______. (θ is real number)

Options

  • `1/2`

  • `sqrt(3)/2`

  • `sqrt(2)`

  • `(2sqrt(3))/4`

MCQ
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Solution

The maximum value of Δ = `|(1, 1, 1),(1, 1 + sin theta, 1),(1 + cos theta, 1, 1)|` is `1/2`. (θ is real number)

Explanation:

Δ = `|(1, 1, 1),(1, 1 + sin theta, 1),(1 + cos theta, 1, 1)|`

[Applying C1 → C1 – C1 and C2 → C2 – C3]

= `|(0, 0, 1),(0, sin theta, 1),(cos theta, 0, 1)|`

= – sin θ · cos θ

= `-1/2 * 2 sin theta cos theta`

= `- 1/2 sin 2theta`

So, maximum value of Δ is `1/2` when sin 2θ = –1.

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Chapter 4: Determinants - Exercise [Page 81]

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NCERT Exemplar Mathematics [English] Class 12
Chapter 4 Determinants
Exercise | Q 31 | Page 81

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