Last updated at April 21, 2021 by Teachoo

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Ex 10.2, 15 Find the position vector of a point R which divides the line joining two points P and Q whose position vectors are ๐ ฬ + 2๐ ฬ โ ๐ ฬ and โ ๐ ฬ + ๐ ฬ + ๐ ฬ respectively, in the ratio 2 : 1 (i) internally (๐๐) โ= ๐ ฬ + 2๐ ฬ โ ๐ ฬ (๐๐) โ= โ ๐ ฬ + ๐ ฬ + ๐ ฬ Position vector of R = (2.(๐๐) โ + 1.(๐๐) โ)/(2 + 1) (๐๐ ) โ = (2(โ๐ ฬ" + " ๐ ฬ" + " ๐ ฬ ) + 1(๐ ฬ" +" 2๐ ฬ" + " ๐ ฬ))/3 = (โ2๐ ฬ + 2๐ ฬ + 2๐ ฬ + ๐ ฬ + 2๐ ฬ โ( ๐) ฬ)/3 = (โ๐ ฬ + 4๐ ฬ + ๐ ฬ)/3 Thus, position vector of R dividing P and Q internally is (โ๐)/๐ ๐ ฬ + ๐/๐ ๐ ฬ + ๐/๐ ๐ ฬ Ex 10.2, 15 Find the position vector of a point R which divides the line joining two points P and Q whose position vectors are ๐ ฬ + 2 ๐ ฬ โ ๐ ฬ and โ ๐ ฬ + ๐ ฬ + ๐ ฬ respectively, in the ratio 2 : 1 (ii) externally Position vector of R = (2(๐๐) โ โ 1(๐๐) โ)/(2 โ 1) (๐๐ ) โ = (2(โ๐ ฬ" + " ๐ ฬ" + " ๐ ฬ )โ1(๐ ฬ" + " 2๐ ฬ" โ " ๐ ฬ))/(2โ1) (๐๐ ) โ = (โ2๐ ฬ + 2๐ ฬ + 2๐ ฬ โ ๐ ฬ โ 2๐ ฬ + ๐ ฬ)/(2โ1) (๐๐ ) โ = โ3๐ ฬ + 3๐ ฬ Thus, Position vector of R dividing P and Q externally is โ3๐ ฬ + 3๐ ฬ

Ex 10.2

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Ex 10.2, 15 Important You are here

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Ex 10.2, 18 (MCQ) Important

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About the Author

Davneet Singh

Davneet Singh is a graduate from Indian Institute of Technology, Kanpur. He has been teaching from the past 10 years. He provides courses for Maths and Science at Teachoo.