જો બે સદીશ \(\vec{A}\) અને \(\vec{B}\) માટે \(\vec{A} . \vec{B}=[\vec{A} \times \vec{B}]\) સંબધ સાચો હોય, તો \([\vec{A}-\vec{B}]\) નું મૂલ્ય કેટલું હશે?

A \(\sqrt{A^{2}+B^{2}-\sqrt{2} A B}\)
B \(\sqrt{A^{2}+B^{2}}\)
C \(\sqrt{A^{2}+B^{2}+\sqrt{2} A B}\)
D \(\sqrt{A^{2}+B^{2}+\sqrt{2} A B}\)

Verified Solution

Answer & Solution

Correct Answer

(A) \(\sqrt{A^{2}+B^{2}-\sqrt{2} A B}\)

Step-by-step Solution

Detailed explanation

\(\vec{A} \vec{B}=|\vec{A} \times \vec{B}|\) \(A B \cos \theta=A B \sin \theta \Rightarrow \theta=45^{\circ}\) \(|\vec{A}-\vec{B}|=\sqrt{A^{2}+B^{2}-2 A B \cos 45^{\circ}}\) \(=\sqrt{A^{2}+B^{2}-\sqrt{2} A B}\)

Apply the relevant identity from the chapter and substitute the values established in the previous step, keeping the original constraint in view.

Use the simplified expression to isolate the unknown, then plug the result back into the question setup to confirm the working is internally consistent.

Cross-check against a boundary or limiting case. Both the dimensional balance and the qualitative behaviour at the extreme should agree with the candidate answer.

Combine the steps above to identify the correct option. The remaining choices each fail at least one of the consistency, dimensional, or boundary checks.

Same subject

સૂચિ - I સાથે સૂચિ – II ને જોડો :

સૂચિ – I	સૂચિ – II
A. શ્યાનતા ગુણાંક	I. \(\left[M L^{-1} T^{-2}\right]\)
B. પૃષ્ઠતાણ	II. \(\left[M L^2 T^{-2}\right]\)
C. દબાણ	III. \(\left[M L^0 T^{-2}\right]\)
D. પૃષ્ઠ ઉર્જા	IV. \(\left[M L^{-1} T^{-1}\right]\)

નીચે આપેલા વિકલ્પોમાંથી સાચો ઉત્તર પસંદ કરો :

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