The position vectors of point A,B and C are 9i-10j , 4i+2j and Ki-2j respectively.Find the value of k if the point A,B and c are collinear. Help me solve this.thank u

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- Oct 5th 2012, 07:34 AMsharmalaPlease help me to solve this vector question.....
The position vectors of point A,B and C are 9i-10j , 4i+2j and Ki-2j respectively.Find the value of k if the point A,B and c are collinear. Help me solve this.thank u

- Oct 5th 2012, 08:42 AMHallsofIvyRe: Please help me to solve this vector question.....
What is the vector from A to B? What is the vector from A to C? Do you know what "colinear"

**means**? - Oct 5th 2012, 08:44 AMKrahlRe: Please help me to solve this vector question.....
Do you know what collinear means?

- Oct 5th 2012, 08:46 AMSorobanRe: Please help me to solve this vector question.....
Hello, sharmala1

Quote:

The position vectors of points A, B and C are 9i-10j , 4i+2j and Ki-2j respectively.

Find the value of k if the points A,B and c are collinear.

If are collinear, then: .

We have: .

. . . . . . . . .

Hence: .

From [2]: .

Subtitute into [1]: .

Therefore: .

- Oct 5th 2012, 09:13 AMKrahlRe: Please help me to solve this vector question.....
Equating the gradients can also be done.

(9,-10),(4,2),(k,-2)

and solve for k to get what Soroban got.