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The length of the perpendicular drawn fr...

The length of the perpendicular drawn from the point `(3, -1, 11)` to the line `(x)/(2)=(y-2)/(3)=(z-3)/(4)` is

A

`sqrt(66)`

B

`sqrt(29)`

C

`sqrt(33)`

D

`sqrt(53)`

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The correct Answer is:
To find the length of the perpendicular drawn from the point \( P(3, -1, 11) \) to the line given by the symmetric equations \( \frac{x}{2} = \frac{y-2}{3} = \frac{z-3}{4} \), we can follow these steps: ### Step 1: Parametrize the line The symmetric equations can be rewritten in parametric form. Let \( t \) be the parameter. Then we have: - \( x = 2t \) - \( y = 3t + 2 \) - \( z = 4t + 3 \) ### Step 2: Find a point on the line From the parametric equations, we can find a point on the line by substituting \( t = 0 \): - When \( t = 0 \), the point on the line is \( Q(0, 2, 3) \). ### Step 3: Find the direction vector of the line The direction vector \( \vec{d} \) of the line can be derived from the coefficients of \( t \) in the parametric equations: - \( \vec{d} = (2, 3, 4) \). ### Step 4: Find the vector from point \( P \) to point \( Q \) The vector \( \vec{PQ} \) from point \( P(3, -1, 11) \) to point \( Q(0, 2, 3) \) is given by: \[ \vec{PQ} = Q - P = (0 - 3, 2 - (-1), 3 - 11) = (-3, 3, -8). \] ### Step 5: Use the formula for the length of the perpendicular The length of the perpendicular \( d \) from point \( P \) to the line can be calculated using the formula: \[ d = \frac{|\vec{PQ} \cdot (\vec{d} \times \vec{PQ})|}{|\vec{d}|}. \] ### Step 6: Calculate \( \vec{d} \times \vec{PQ} \) To find \( \vec{d} \times \vec{PQ} \): \[ \vec{d} = (2, 3, 4), \quad \vec{PQ} = (-3, 3, -8). \] Using the determinant to calculate the cross product: \[ \vec{d} \times \vec{PQ} = \begin{vmatrix} \hat{i} & \hat{j} & \hat{k} \\ 2 & 3 & 4 \\ -3 & 3 & -8 \end{vmatrix} = \hat{i}(3 \cdot -8 - 4 \cdot 3) - \hat{j}(2 \cdot -8 - 4 \cdot -3) + \hat{k}(2 \cdot 3 - 3 \cdot -3). \] Calculating each component: - \( \hat{i}(-24 - 12) = -36\hat{i} \) - \( \hat{j}(-16 + 12) = -4\hat{j} \) - \( \hat{k}(6 + 9) = 15\hat{k} \) Thus, \[ \vec{d} \times \vec{PQ} = (-36, -4, 15). \] ### Step 7: Calculate the magnitude of \( \vec{d} \times \vec{PQ} \) \[ |\vec{d} \times \vec{PQ}| = \sqrt{(-36)^2 + (-4)^2 + (15)^2} = \sqrt{1296 + 16 + 225} = \sqrt{1537}. \] ### Step 8: Calculate the magnitude of \( \vec{d} \) \[ |\vec{d}| = \sqrt{2^2 + 3^2 + 4^2} = \sqrt{4 + 9 + 16} = \sqrt{29}. \] ### Step 9: Calculate the length of the perpendicular Now substituting back into the formula for \( d \): \[ d = \frac{|\vec{PQ} \cdot (\vec{d} \times \vec{PQ})|}{|\vec{d}|}. \] First, we need to calculate \( \vec{PQ} \cdot (\vec{d} \times \vec{PQ}) \): \[ \vec{PQ} \cdot (-36, -4, 15) = (-3)(-36) + (3)(-4) + (-8)(15) = 108 - 12 - 120 = -24. \] Thus, \[ d = \frac{|-24|}{\sqrt{29}} = \frac{24}{\sqrt{29}}. \] ### Final Step: Simplifying the result To express the length in a more standard form, we can rationalize the denominator: \[ d = \frac{24\sqrt{29}}{29}. \] ### Conclusion The length of the perpendicular drawn from the point \( (3, -1, 11) \) to the line is \( \frac{24\sqrt{29}}{29} \). ---
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ARIHANT MATHS-THREE DIMENSIONAL COORDINATE SYSTEM-Exercise (Questions Asked In Previous 13 Years Exam)
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  2. If the angle between the line x=(y-1)/(2)=(z-3)(lambda) and the plane ...

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  3. Statement-I The point A(1, 0, 7) is the mirror image of the point B(1,...

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  4. The length of the perpendicular drawn from the point (3, -1, 11) to th...

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  5. The distance of the point (1,-5,""9) from the plane x-y+z=5 measured a...

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  6. A line AB in three-dimensional space makes angles 45^(@) and 120^(@) w...

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  7. Statement-I The point A(3, 1, 6) is the mirror image of the point B(1,...

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  8. Let the line (x-2)/(3)=(y-1)/(-5)=(z+2)/(2) lies in the plane x+3y-alp...

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  9. The projection of a vector on the three coordinate axes are 6, -3, 2, ...

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  10. The line passing through the points (5, 1, a) and (3, b, 1) crosses th...

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  11. If the straight lines (x-1)/(k)=(y-2)/(2)=(z-3)/(3) and (x-2)/(3)=(y-3...

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  12. Let L be the line of intersection of the planes 2x+3y+z=1 and x+3y+2z=...

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  13. If a line makes an angle (pi)/(4) with the positive directions of each...

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  14. If (2, 3, 5) is one end of a diameter of the sphere x^(2)+y^(2)+z^(2)-...

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  15. The two lines x=ay+b, z=cy+d and x=a'y+b', z=c'y+d' are perpendicular ...

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  16. The image of the point (-1, 3, 4) in the plane x-2y=0 is

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  17. If the plane 2ax-3ay+4az+6=0 passes through the mid point of the line ...

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  18. If the angle theta between the line (x+1)/(1)=(y-1)/(2)=(z-2)/(2) and ...

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  19. The angle between the lines 2x=3y=-z and 6x=-y=-4z is

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  20. The plane x+2y-z=4 cuts the sphere x^(2)+y^(2)+z^(2)-x+z-2=0 in a circ...

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