NCERT Class 12 · Ch 10 Exercise 10.3 · Q6
NCERT Class 12 Maths · Chapter 10 Vector Algebra · Exercise 10.3 Question 6
Find |a|,|b| if (a+b)·(a−b)=8 and |a|=8|b|.
💡 Concept Hints
- Write the vector components and identify the required direction or geometric relation.
- Use the magnitude, dot-product, cross-product or section formula that matches the requested quantity.
✅ Step-by-Step Solution
Final Answer: |b|=√(8/63), |a|=8√(8/63).
- The dot product expands to |a|²−|b|²=8.
- Put |b|=r≥0 and |a|=8r. Then 64r²−r²=8, giving r²=8/63. Take the nonnegative root.
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