CBSE Class 12 Mathematics 2026 Main Paper 65/1/2 · Q81 Marksvector_algebra
CBSE Class 12 Mathematics 2026 Main Paper 65/1/2 · Question 8 (Vector Algebra)
If |a| = 8, |b| = 3 and |a × b| = 12, then the value of |a · b| is
✅ Step-by-Step Solution
Final Answer: (C) 12√3
- |a×b| = |a||b| sinθ = 24 sinθ = 12 ⇒ sinθ = 1/2.
- The absolute value of cos θ is √3/2; its sign need not be positive.
- |a·b| = |a||b| |cos θ| = 24·(√3/2) = 12√3.
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