If  find a unit vector in the direction of . from Mathematic

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 Multiple Choice QuestionsShort Answer Type

61. Find the direction cosines of the vector joining the points A (1, 2, – 3) and B (– 1, – 2. 1). directed from A to B.
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62. If A is (a1 , a2 , a3), AB with rightwards arrow on top is vector straight b with rightwards arrow on top space equals space straight b subscript 1 straight i with hat on top space plus space straight b subscript 2 straight j with hat on top space plus space straight b subscript 3 straight k with hat on top, find the coordinates of B.
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63.

If PQ with rightwards arrow on top space equals space 3 straight i with hat on top space plus space 2 straight j with hat on top space minus space straight k with hat on top and the coordinates of P are (1, – 1, – 2), find the coordinates of Q.

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64. Find the values of x and y so that the vectors 2 straight i with hat on top space plus space 3 straight j with hat on top and straight x straight i with hat on top space plus space straight y straight j with hat on top are equal.
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65.

Let straight a with rightwards arrow on top space equals space straight i with hat on top space plus space 2 space straight j with hat on top and straight b with rightwards arrow on top space equals space 2 straight i with hat on top space plus space straight j with hat on top. Is open vertical bar straight a with rightwards arrow on top close vertical bar space equals space open vertical bar straight b with rightwards arrow on top close vertical bar space ? Are the vectors straight a with rightwards arrow on top space and space straight b with rightwards arrow on top equal?

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66. Find a unit vector in the direction of straight a 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 6 space straight k with hat on top.
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67. Find unit vector in the direction of vector straight a with rightwards arrow on top space equals space 2 space straight i with hat on top space plus space 3 space straight j with hat on top space plus space straight k with hat on top.
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68. Find the unit vector in the direction of the sum of the vectors straight a with rightwards arrow on top space equals space 2 straight i with hat on top space plus space 2 space straight j with hat on top space minus space 5 space straight k with hat on top space and space space straight b with rightwards arrow on top space equals space 2 straight i with hat on top space plus space straight j with hat on top space plus 3 space straight k with hat on top

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69. If straight a with rightwards arrow on top space equals space straight i with hat on top space plus space 2 straight j with hat on top space minus space straight k with hat on top space and space straight b with rightwards arrow on top space equals space 3 straight i with hat on top space plus space straight j with hat on top space minus space 5 space straight k with hat on top comma find a unit vector in the direction of straight a with rightwards arrow on top space minus space straight b with rightwards arrow on top.


Here,          straight a with rightwards arrow on top space equals space straight i with hat on top space space plus space 2 straight j with hat on top space minus space straight k with hat on top comma space space straight b with rightwards arrow on top equals space 3 space straight i with hat on top space plus space straight j with hat on top space minus space 5 space straight k with hat on top
therefore space space space space straight a with rightwards arrow on top space minus space straight b with rightwards arrow on top space equals space left parenthesis straight i with hat on top space plus space 2 space straight j with hat on top space minus space straight k with hat on top right parenthesis space minus space left parenthesis 3 space straight i with hat on top space plus space straight j with hat on top space minus space 5 space straight k with hat on top right parenthesis space equals space minus 2 space straight i with hat on top space plus space straight j with hat on top space plus space 4 space straight k with hat on top
therefore space space space space space space open vertical bar straight a with rightwards arrow on top minus straight b with rightwards arrow on top close vertical bar space equals space square root of left parenthesis negative 2 right parenthesis squared plus left parenthesis 1 right parenthesis squared plus left parenthesis 4 right parenthesis squared end root space equals space square root of 4 plus 1 plus 16 end root space equals space square root of 21
therefore space space space space space unit space vector space in space the space direction space of space straight a with rightwards arrow on top space minus space straight b with rightwards arrow on top
                  equals space fraction numerator straight a with rightwards arrow on top space minus space straight b with rightwards arrow on top over denominator open vertical bar straight a with rightwards arrow on top space minus space straight b with rightwards arrow on top close vertical bar end fraction space equals space fraction numerator 1 over denominator square root of 21 end fraction space left parenthesis negative 2 space straight i with hat on top space plus space straight j with hat on top space space plus space 4 space straight k with hat on top right parenthesis
equals space minus fraction numerator 2 over denominator square root of 21 end fraction straight i with hat on top space plus space fraction numerator 1 over denominator square root of 21 end fraction straight j with hat on top space plus space fraction numerator 4 over denominator square root of 21 end fraction straight k with hat on top.

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70. Find the unit vector in the direction of the vector 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 2 space straight k with hat on top.
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