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Evaluate δ = ∣ ∣ ∣ ∣ 0 Sin α − Cos α − Sin α 0 Sin β Cos α − Sin β 0 ∣ ∣ ∣ ∣

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प्रश्न

Evaluate
\[∆ = \begin{vmatrix}0 & \sin \alpha & - \cos \alpha \\ - \sin \alpha & 0 & \sin \beta \\ \cos \alpha & - \sin \beta & 0\end{vmatrix}\]

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उत्तर

Let 

\[∆ = \begin{vmatrix}0 & \sin\alpha & - \cos\alpha \\ - \sin\alpha & 0 & \sin\beta \\ \cos\alpha & - \sin\beta & 0\end{vmatrix}\]

\[∆ = \left( - 1 \right)^{1 + 1} 0 \left( 0 + \sin^2 \beta \right) + \left( - 1 \right)^{1 + 2} \sin\alpha\left( 0 - \sin\beta\cos\alpha \right) + \left( - 1 \right)^{1 + 3} \left( - \cos\alpha \right)\left( \sin\alpha\sin\beta - 0 \right) \left[ \text{ Expanding along } R_1 \right]\]
\[ = 0\left( 0 + \sin^2 \beta \right) - \sin\alpha\left( 0 - \sin\beta\cos\alpha \right) - \cos\alpha\left( \sin\alpha\sin\beta - 0 \right)\]
\[ = \sin\alpha\sin\beta\cos\alpha - \sin\alpha\sin\beta\cos\alpha\]
\[ = 0\]

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अध्याय 5: Determinants - Exercise 6.1 [पृष्ठ १०]

APPEARS IN

आर.डी. शर्मा Mathematics Volume 1 and 2 [English] Class 12
अध्याय 5 Determinants
Exercise 6.1 | Q 6 | पृष्ठ १०

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