Class 12 Vector Algebra · Short Answer2 Marksdot_product_angle
Class 12 Maths · Vector Algebra · Short Answer #107
Unit vectors a,b have a+b also unit. Find their angle.
✅ Step-by-Step Solution
Final Answer: 2π/3
- Expand |a+b|²=|a|²+|b|²+2a·b.
- Thus 1=2+2cos θ, giving cos θ=−1/2.
- Therefore θ=2π/3.
📋 CBSE Stepwise Marking Scheme
- [0.5 marks] Expand |a+b|²=|a|²+|b|²+2a·b.
- [1 mark] Thus 1=2+2cos θ, giving cos θ=−1/2.
- [0.5 marks] Therefore θ=2π/3.
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