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Question
Find the position vector of a point R which divides the line joining the two points P and Q with position vectors `vec"OP" = 2vec"a" + vec"b"` and `vec"OQ" = vec"a" - 2vec"b"`, respectively, in the ratio 1:2 internally
Solution
The position vector of the point R dividing the join of P and Q internally in the ratio 1:2 is given by
`vec"OR" = (2(2vec"a" + vec"b") + 1(vec"a" - 2vec"b"))/(1 + 2)`
= `(5vec"a")/3`.
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