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If cos2θ = 0, then |0cosθsinθcosθsinθ0sinθ0cosθ|2 = ______. - Mathematics

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प्रश्न

If cos2θ = 0, then `|(0, costheta, sin theta),(cos theta, sin theta,0),(sin theta, 0, cos theta)|^2` = ______.

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उत्तर

If cos2θ = 0, then `|(0, costheta, sin theta),(cos theta, sin theta,0),(sin theta, 0, cos theta)|^2` = `- 1/sqrt(2)`.

Explanation:

Δ = `|(0, costheta, sin theta),(cos theta, sin theta,0),(sin theta, 0, cos theta)|^2`

 = `0 - cos theta(costheta) + sintheta(0- sin^2theta)`

= `-(cos^3theta + sin^2theta)`

cos2θ = 0

⇒ 2θ = `pi/2`

⇒ θ = `pi/4`

∴ Δ = `-(cos^3  pi/4 + sin^3  pi/4)`

= `-((1/sqrt(2))^3 +(1/sqrt(2))^3)`

=`- 1/sqrt(2)`

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अध्याय 4: Determinants - Exercise [पृष्ठ ८३]

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एनसीईआरटी एक्झांप्लर Mathematics [English] Class 12
अध्याय 4 Determinants
Exercise | Q 41 | पृष्ठ ८३

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