Class 12 Vector Algebra · Short Answer2 Markssection_formula
Class 12 Maths · Vector Algebra · Short Answer #51
X,Y have position vectors 3a + b and a − 3b. Find the position vector of Z dividing XY externally in the ratio 2:1.
✅ Step-by-Step Solution
Final Answer: −a − 7b.
- For external division XZ:ZY = 2:1, use z = [2y − x]/(2 − 1).
- Substitute: z = 2(a − 3b) − (3a + b) = 2a − 6b − 3a − b.
- Therefore z = −a − 7b.
📋 CBSE Stepwise Marking Scheme
- [0.5 marks] For external division XZ:ZY = 2:1, use z = [2y − x]/(2 − 1).
- [1 mark] Substitute: z = 2(a − 3b) − (3a + b) = 2a − 6b − 3a − b.
- [0.5 marks] Therefore z = −a − 7b.
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