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Tamil Nadu Board of Secondary EducationHSC Science Class 12

Determine whether the three vectors ijkijk2i^+3j^+k^,i^-2j^+2k^ and ijk3i^+j^+3k^ are coplanar

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Question

Determine whether the three vectors `2hat"i" + 3hat"j" + hat"k", hat"i" - 2hat"j" + 2hat"k"` and `3hat"i" + hat"j" + 3hat"k"` are coplanar

Sum
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Solution

Let `vec"a" = 2vec"i" + vec"j" + vec"k"`

`vec"b" = vec"i" - 2vec"j" + 2vec"k"`

`vec"c" = 3vec"i" + vec"j" + 3vec"k"`

We know that `vec"a",  vec"b",  vec"c"` are coplanar if and only if `[vec"a",  vec"b",  vec"c"]` = 0

`[vec"a",  vec"b",  vec"c"] = |(2, 3, 1),(1, -2, 2),(3, 1, 3)|`

= `2(- 6 - 2) - 3(3 - 6) + (1 + 6)`

= −16 + 9 + 7

= 0

∴ Gives vectors are coplanar

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Chapter 6: Applications of Vector Algebra - Exercise 6.2 [Page 237]

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Samacheer Kalvi Mathematics - Volume 1 and 2 [English] Class 12 TN Board
Chapter 6 Applications of Vector Algebra
Exercise 6.2 | Q 6 | Page 237

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