are unit vectors,  Suppose that   and the angle between B a

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 Multiple Choice QuestionsLong Answer Type

291.

If straight a with rightwards arrow on top space equals space straight i with hat on top space plus space straight j with hat on top space plus space straight k with hat on top space and straight b with rightwards arrow on top space equals space straight j with hat on top space minus space straight k with hat on top.  Find a vector straight c with rightwards arrow on top such that straight a with rightwards arrow on top cross times space straight c with rightwards arrow on top space equals space straight b with rightwards arrow on top and straight a with rightwards arrow on top. space straight c with rightwards arrow on top space equals space 3.

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292.

Let straight a with rightwards arrow on top space equals straight i with hat on top space plus space 4 space straight j with hat on top space plus space 2 space straight k with hat on top comma space space space space space straight b with rightwards arrow on top space equals space 3 space straight i with hat on top space minus space 2 space straight j with hat on top space plus space space 7 space straight k with hat on top and straight c with rightwards arrow on top space equals space 2 space straight i with hat on top space minus space straight j with hat on top space plus space 4 space straight k with hat on top. Find a vector straight d with rightwards arrow on top which is perpendicular to both straight a with rightwards arrow on top space and space straight b with rightwards arrow on top comma space space straight c with rightwards arrow on top. space straight d with rightwards arrow on top space equals space 15.

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293. If with reference to a right handed system of mutually perpendicular unit vector unit vector straight i with hat on top comma space straight j with hat on top comma space straight k with hat on top

express straight beta with rightwards arrow on top in the form straight beta with rightwards arrow on top in the form straight beta with rightwards arrow on top space equals space straight beta with rightwards arrow on top subscript 1 space equals space straight beta with rightwards arrow on top subscript 1 space plus space straight beta with rightwards arrow on top subscript 2 space end subscript space where space stack straight beta subscript 1 with rightwards arrow on top space is space parallel space to space straight alpha space and space stack straight beta subscript 2 with rightwards arrow on top space is space perpendicular space to space straight alpha with rightwards arrow on top.
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 Multiple Choice QuestionsShort Answer Type

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294. straight A with rightwards arrow on top comma space straight B with rightwards arrow on top comma space straight C with rightwards arrow on top are unit vectors,  Suppose that  straight A with rightwards arrow on top. space straight B with rightwards arrow on top space equals space straight A with rightwards arrow on top. space straight C with rightwards arrow on top space equals space 0 and the angle between B and C is straight pi over 6. Prove that straight A with rightwards arrow on top space equals plus-or-minus 2 space open parentheses straight B with rightwards arrow on top space cross times space straight C with rightwards arrow on top close parentheses.


Since  straight A with rightwards arrow on top. space straight B with rightwards arrow on top space equals space straight A with rightwards arrow on top. space straight C with rightwards arrow on top space equals 0
therefore space space space space straight A with rightwards arrow on top space is space perpendicular space to space straight B with rightwards arrow on top space as space well space as space straight C with rightwards arrow on top
therefore space space space straight A with rightwards arrow on top space is space parallel space to space straight B with rightwards arrow on top space cross times space straight C with rightwards arrow on top
Let straight A with rightwards arrow on top space equals space straight lambda open parentheses straight B with rightwards arrow on top space cross times space straight C with rightwards arrow on top close parentheses                                                        ...(1)
where straight lambda is some scalar
therefore space space space open vertical bar straight A with rightwards arrow on top close vertical bar space equals space open vertical bar straight lambda close vertical bar space space open vertical bar straight B with rightwards arrow on top space cross times space straight C with rightwards arrow on top close vertical bar space space space space space space space rightwards double arrow space space space open vertical bar straight A with rightwards arrow on top close vertical bar space equals space open vertical bar straight lambda close vertical bar space space open vertical bar straight B with rightwards arrow on top close vertical bar space open vertical bar straight C with rightwards arrow on top close vertical bar space space sin space straight pi over 6 space open vertical bar straight n with hat on top close vertical bar
where straight n with hat on top is perpendicular to straight B with rightwards arrow on top space as space well space as space straight C with rightwards arrow on top.
rightwards double arrow space space space space space 1 space equals space open vertical bar straight lambda close vertical bar space left parenthesis 1 right parenthesis thin space left parenthesis 1 right parenthesis space space open parentheses 1 half close parentheses space left parenthesis 1 right parenthesis space space space space space space space space space space space space space space space open square brackets because space space space straight A with rightwards arrow on top comma space straight B with rightwards arrow on top comma space straight C with rightwards arrow on top space are space unit space vectors close square brackets.
therefore space space space space space from space left parenthesis 1 right parenthesis comma space space space we space get comma space space straight A with rightwards arrow on top space space equals plus-or-minus 2 space open parentheses straight B with rightwards arrow on top space cross times space straight C with rightwards arrow on top close parentheses


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 Multiple Choice QuestionsLong Answer Type

295. Give space space space straight a with rightwards arrow on top space equals space 1 over 7 left parenthesis 2 space straight i with hat on top space plus space 3 space straight j with hat on top space plus space 6 space straight k with hat on top right parenthesis comma space space straight b with rightwards arrow on top space equals space 1 over 7 left parenthesis 3 space straight i with hat on top space minus space 6 space straight j with hat on top space plus space 2 space straight k with hat on top right parenthesis comma
space space space space space space space space space space space space space space straight c with rightwards arrow on top space equals space 1 over 7 left parenthesis 6 space straight i with hat on top space plus space 2 space straight j with hat on top space minus space 3 space straight k with hat on top right parenthesis comma
straight i with hat on top comma space straight j with hat on top comma space straight k with hat on top being a right-handed orthogonal system of unit vectors in space. Show that straight a with rightwards arrow on top comma space straight b with rightwards arrow on top comma space straight c with rightwards arrow on top in another such system.
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 Multiple Choice QuestionsShort Answer Type

296. Find the value of the following:
straight i with hat on top. space open parentheses straight j with hat on top space cross times space straight k with hat on top close parentheses space plus space straight j with hat on top. space space left parenthesis straight i with hat on top space cross times space straight k with hat on top right parenthesis space plus space space straight k with hat on top. space space left parenthesis straight i with hat on top space cross times space straight j with hat on top right parenthesis
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297. Find the value of the following:
straight i with hat on top. space left parenthesis straight j with hat on top space cross times space straight k with hat on top right parenthesis space plus space straight j with hat on top space cross times space left parenthesis straight k with hat on top space cross times space straight i with hat on top right parenthesis space plus space straight k with hat on top space cross times space left parenthesis straight i with hat on top space cross times space straight j with hat on top right parenthesis
space
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298. Find the value of the following:
straight i with hat on top space cross times space left parenthesis straight j with hat on top space cross times space straight k with hat on top right parenthesis space plus space straight j with hat on top space cross times space left parenthesis straight k with hat on top space cross times space straight i with hat on top right parenthesis space plus space straight k with hat on top space cross times space left parenthesis straight i with hat on top space cross times space straight j with hat on top right parenthesis
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 Multiple Choice QuestionsMultiple Choice Questions

299.

Let vectors straight a with rightwards arrow on top space and space straight b with rightwards arrow on top be such that open vertical bar straight a with rightwards arrow on top close vertical bar space equals 3 space space space and space open vertical bar straight b with rightwards arrow on top close vertical bar space equals space fraction numerator square root of 2 over denominator 3 end fraction comma then straight a with rightwards arrow on top space cross times space straight b with rightwards arrow on top is a unit vector, if the angle betweeen straight a with rightwards arrow on top space and space straight b with rightwards arrow on top is 

  • straight pi divided by 6
  • straight pi divided by 4
  • straight pi divided by 3
  • straight pi divided by 3
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300.

If straight theta is the angle between any two vectors straight a with rightwards arrow on top space and space straight b with rightwards arrow on top comma then open vertical bar straight a with rightwards arrow on top. space straight b with rightwards arrow on top close vertical bar space equals space open vertical bar straight a with rightwards arrow on top space cross times space straight b with rightwards arrow on top close vertical bar when straight theta is equal to 

  • 0

  • straight pi over 4
  • straight pi over 2
  • straight pi over 2
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