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If veca,vecb,vecc & vecd are position ve...

If `veca,vecb,vecc & vecd` are position vector of point A,B,C and D respectively in 3-D space no three of A,B,C,D are colinear and satisfy the relation `3veca-2vecb+vecc-2vecd=0` then (a) A, B, C and D are coplanar (b) The line joining the points B and D divides the line joining the point A and C in the ratio of `2:1` (c) The line joining the points A and C divides the line joining the points B and D in the ratio of `1:1` (d)The four vectors `veca, vecb, vec c and vecd` are linearly dependent .

A

A, B, C and D are coplanar

B

The line joining the points B and D divides the line joining the point A and C in the ratio of `2:1`

C

The line joining the points A and C divides the line joining the points B and D in the ratio of `1:1`

D

The four vectors `veca, vecb, vec c and vecd` are linearly dependent .

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To solve the problem, we start with the given relation among the position vectors of points A, B, C, and D: \[ 3\vec{a} - 2\vec{b} + \vec{c} - 2\vec{d} = 0 \] ### Step 1: Rearranging the Equation We can rearrange the equation to isolate the terms involving vectors A, C, B, and D: \[ 3\vec{a} + \vec{c} = 2\vec{b} + 2\vec{d} \] ### Step 2: Dividing by 4 Next, we divide the entire equation by 4 to simplify it: \[ \frac{3\vec{a} + \vec{c}}{4} = \frac{2\vec{b} + 2\vec{d}}{4} \] This simplifies to: \[ \frac{3\vec{a} + \vec{c}}{4} = \frac{1}{2}(\vec{b} + \vec{d}) \] ### Step 3: Interpreting the Result The left-hand side represents a point that divides the line segment joining points A and C in the ratio of 3:1. The right-hand side represents a point that divides the line segment joining points B and D in the ratio of 1:1. ### Step 4: Conclusion about Ratios From the above interpretation: - The line joining points A and C is divided by the point in the ratio 3:1. - The line joining points B and D is divided by the same point in the ratio 1:1. ### Step 5: Checking the Options Now, we can evaluate the options provided: (a) **A, B, C, and D are coplanar.** - Since the two lines intersect at a common point, they lie in the same plane. Thus, this option is correct. (b) **The line joining points B and D divides the line joining points A and C in the ratio of 2:1.** - This is incorrect as we found the ratio to be 3:1. (c) **The line joining points A and C divides the line joining points B and D in the ratio of 1:1.** - This is correct because the point divides the line BD in the ratio of 1:1. (d) **The four vectors are linearly dependent.** - Since we have a non-trivial linear combination of the vectors equating to zero, this option is also correct. ### Final Answer The correct options are (a), (c), and (d).
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VK JAISWAL ENGLISH-VECTOR & 3DIMENSIONAL GEOMETRY-Exercise-2 : One or More than One Answer is/are Correct
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  5. The value(s) of mu for which the straight lines vecr=3hati-2hatj-4hatk...

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  6. If hati xx [ (veca-hatj) xxhati]+ hatj xx [(veca - hatk)xx hatj] +hatk...

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  7. [vecaxx vecb " " vecc xx vecd " " vecexx vecf] is equal to (a)[veca...

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  8. If veca,vecb,vecc & vecd are position vector of point A,B,C and D resp...

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  9. veca and vecc are unit vectors and |vecb|=4 the angle between veca and...

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  10. Consider the lines x=y=z and line 2x+y+z-1=0=3x+y+2z-2, then

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  11. If (veca xx vecb) xx (vec c xx vecd)=h veca+k vecb=r vec c+s vecd, wh...

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  12. If (veca xx vecb) xx (vec c xx vecd)=h veca+k vecb=r vec c+s vecd, wh...

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  13. Let a be a real number and vec alpha = hati +2hatj, vec beta=2hati+a h...

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  14. The volume of a right triangular prism ABCA(1)B(1)C(1) is equal to 3 c...

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  16. If a line has a vector equation, vecr=2hati +6hatj+lambda(hati-3hatj) ...

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