Magnitude of cross product of two vectors

Practice question

Question

Vectors a\=5i^−4j^ and b\=3i^+6j^ are given. What is the magnitude of a×b?

Options

Choose one · Correct answer highlighted

40 41 42 Correct 43

Explanation

a×b = |i^j^k^5−40360| = k^(5×6−(−4)×3) = k^(30+12) = 42k^. Magnitude = 42. As per NCERT, applying relevant law/formula with correct units and sign convention leads to 42. This satisfies dimensional consistency and physical conditions given, so option C is scientifically correct.

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