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Shortest distance between the lines (x-3...

Shortest distance between the lines `(x-3)/1 = (y-8)/4 = (z-3)/22` and ` (x+3)/1 = (y+7)/1 = (z-6)/7` is

A

`3sqrt30`

B

`2sqrt30`

C

`sqrt30`

D

`4sqrt30`

Text Solution

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To find the shortest distance between the two given lines, we can use the formula for the distance \( d \) between two skew lines represented in vector form. The lines are given as: 1. \(\frac{x-3}{1} = \frac{y-8}{4} = \frac{z-3}{22}\) 2. \(\frac{x+3}{1} = \frac{y+7}{1} = \frac{z-6}{7}\) ### Step 1: Identify the direction vectors and points on the lines From the first line, we can express it in vector form: - Point on Line 1: \( A(3, 8, 3) \) - Direction vector of Line 1: \( \mathbf{b_1} = (1, 4, 22) \) From the second line, we can express it in vector form: - Point on Line 2: \( B(-3, -7, 6) \) - Direction vector of Line 2: \( \mathbf{b_2} = (1, 1, 7) \) ### Step 2: Find the vector connecting the two points The vector connecting points \( A \) and \( B \) is given by: \[ \mathbf{a_2 - a_1} = B - A = (-3 - 3, -7 - 8, 6 - 3) = (-6, -15, 3) \] ### Step 3: Calculate the cross product of the direction vectors Now, we need to find the cross product \( \mathbf{b_1} \times \mathbf{b_2} \): \[ \mathbf{b_1} = (1, 4, 22), \quad \mathbf{b_2} = (1, 1, 7) \] Using the determinant method for the cross product: \[ \mathbf{b_1} \times \mathbf{b_2} = \begin{vmatrix} \mathbf{i} & \mathbf{j} & \mathbf{k} \\ 1 & 4 & 22 \\ 1 & 1 & 7 \end{vmatrix} \] Calculating the determinant: \[ = \mathbf{i}(4 \cdot 7 - 22 \cdot 1) - \mathbf{j}(1 \cdot 7 - 22 \cdot 1) + \mathbf{k}(1 \cdot 1 - 4 \cdot 1) \] \[ = \mathbf{i}(28 - 22) - \mathbf{j}(7 - 22) + \mathbf{k}(1 - 4) \] \[ = 6\mathbf{i} + 15\mathbf{j} - 3\mathbf{k} \] ### Step 4: Calculate the magnitude of the cross product Now we calculate the magnitude of \( \mathbf{b_1} \times \mathbf{b_2} \): \[ |\mathbf{b_1} \times \mathbf{b_2}| = \sqrt{6^2 + 15^2 + (-3)^2} = \sqrt{36 + 225 + 9} = \sqrt{270} = 3\sqrt{30} \] ### Step 5: Calculate the distance using the formula The distance \( d \) between the two lines is given by: \[ d = \frac{|(\mathbf{a_2 - a_1}) \cdot (\mathbf{b_1} \times \mathbf{b_2})|}{|\mathbf{b_1} \times \mathbf{b_2}|} \] Calculating the dot product \( (\mathbf{a_2 - a_1}) \cdot (\mathbf{b_1} \times \mathbf{b_2}) \): \[ \mathbf{a_2 - a_1} = (-6, -15, 3) \] \[ \mathbf{b_1} \times \mathbf{b_2} = (6, 15, -3) \] \[ (-6, -15, 3) \cdot (6, 15, -3) = (-6 \cdot 6) + (-15 \cdot 15) + (3 \cdot -3) = -36 - 225 - 9 = -270 \] Now substituting back into the distance formula: \[ d = \frac{|-270|}{3\sqrt{30}} = \frac{270}{3\sqrt{30}} = \frac{90}{\sqrt{30}} = 3\sqrt{30} \] ### Final Answer: The shortest distance between the two lines is \( 3\sqrt{30} \).

To find the shortest distance between the two given lines, we can use the formula for the distance \( d \) between two skew lines represented in vector form. The lines are given as: 1. \(\frac{x-3}{1} = \frac{y-8}{4} = \frac{z-3}{22}\) 2. \(\frac{x+3}{1} = \frac{y+7}{1} = \frac{z-6}{7}\) ### Step 1: Identify the direction vectors and points on the lines From the first line, we can express it in vector form: ...
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