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Find the direction of a line segment who...

Find the direction of a line segment whose direction ratios are:
2,-6, 3
2, -1, -2
`-9,6,-2`

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The correct Answer is:
To find the direction cosines of a line segment given its direction ratios, we follow these steps: ### Step 1: Identify the Direction Ratios The direction ratios given are: 1. \( \langle 2, -6, 3 \rangle \) 2. \( \langle 2, -1, -2 \rangle \) 3. \( \langle -9, 6, -2 \rangle \) ### Step 2: Calculate the Magnitude of Each Direction Ratio The magnitude of a vector \( \langle a, b, c \rangle \) is given by: \[ \text{Magnitude} = \sqrt{a^2 + b^2 + c^2} \] #### For the first direction ratio \( \langle 2, -6, 3 \rangle \): \[ \text{Magnitude} = \sqrt{2^2 + (-6)^2 + 3^2} = \sqrt{4 + 36 + 9} = \sqrt{49} = 7 \] #### For the second direction ratio \( \langle 2, -1, -2 \rangle \): \[ \text{Magnitude} = \sqrt{2^2 + (-1)^2 + (-2)^2} = \sqrt{4 + 1 + 4} = \sqrt{9} = 3 \] #### For the third direction ratio \( \langle -9, 6, -2 \rangle \): \[ \text{Magnitude} = \sqrt{(-9)^2 + 6^2 + (-2)^2} = \sqrt{81 + 36 + 4} = \sqrt{121} = 11 \] ### Step 3: Calculate the Direction Cosines The direction cosines are calculated by dividing each component of the direction ratio by its magnitude. #### For the first direction ratio \( \langle 2, -6, 3 \rangle \): \[ \text{Direction Cosines} = \left( \frac{2}{7}, \frac{-6}{7}, \frac{3}{7} \right) \] #### For the second direction ratio \( \langle 2, -1, -2 \rangle \): \[ \text{Direction Cosines} = \left( \frac{2}{3}, \frac{-1}{3}, \frac{-2}{3} \right) \] #### For the third direction ratio \( \langle -9, 6, -2 \rangle \): \[ \text{Direction Cosines} = \left( \frac{-9}{11}, \frac{6}{11}, \frac{-2}{11} \right) \] ### Final Answer The direction cosines for the three sets of direction ratios are: 1. \( \left( \frac{2}{7}, \frac{-6}{7}, \frac{3}{7} \right) \) 2. \( \left( \frac{2}{3}, \frac{-1}{3}, \frac{-2}{3} \right) \) 3. \( \left( \frac{-9}{11}, \frac{6}{11}, \frac{-2}{11} \right) \)

To find the direction cosines of a line segment given its direction ratios, we follow these steps: ### Step 1: Identify the Direction Ratios The direction ratios given are: 1. \( \langle 2, -6, 3 \rangle \) 2. \( \langle 2, -1, -2 \rangle \) 3. \( \langle -9, 6, -2 \rangle \) ...
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Knowledge Check

  • The direction cosines of a line whose direction ratios are 1, -2, 3 are

    A
    `(1)/(2sqrt(14)), (-1)/(sqrt(14)), (3)/(sqrt(14))`
    B
    `(1)/(sqrt(14)), (-2)/(sqrt(14)), (3)/(sqrt(14))`
    C
    `(1)/(2),-1, (3)/(2)`
    D
    `(1)/(3), (-2)/(3), 1 `
  • Direction cosines of a line , whose direction ratios are -2,1,2 are

    A
    `(-2)/3 ,1/3 ,2/3`
    B
    `2/3,(-1)/3,2/3`
    C
    `2/3,1/3,(-2)/3`
    D
    `2/3,1/3,4/3`
  • The acute angle between the lines whose direction ratios are 3, 2, 6 and -2, 1, 2 is

    A
    `cos^(-1)((8)/(21))`
    B
    `cos^(-1)((12)/(21))`
    C
    `cos^(-1)((2)/(21))`
    D
    `cos^(-1)((2)/(3))`
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