Vectors satisfy and . What is ?
Answer and explanation
Correct answer: A.
.
- Step 1: Expand the cross product algebraically using bilinearity and skew-symmetry ( and ):
- Step 2: Find between the vectors using the definition of the dot product: .
- Step 3: Compute .
- Step 4: Evaluate the required magnitude: .
Answer
.
Why not the others: results from an algebraic sign miscalculation ( instead of ), giving coefficient instead of .
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