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Freedom equation of a line is (where ar...

Freedom equation of a line is (where are direction cosines)
`x = x_(1) + lr, y =y_(1) +mr, z=z_(1) + nr,` where:

A

r is the distance of (x,y,z) from `(x_(1), y_(1), z_(1))`

B

`|r|` is the distance of (x,y,z) from `(x_(1),y_(1) ,z_(1))`

C

r is the distance of `(x_(1), y_(1), z_(1))` from the origin

D

none of these

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The correct Answer is:
To solve the problem regarding the freedom equation of a line given by the equations \( x = x_1 + lr \), \( y = y_1 + mr \), and \( z = z_1 + nr \), where \( l, m, n \) are the direction cosines, we will find the distance from the point \( (x_1, y_1, z_1) \) to a point \( (x, y, z) \) on the line. ### Step-by-Step Solution: 1. **Understand the Line Equation**: The equations provided represent a line in three-dimensional space, where \( (x_1, y_1, z_1) \) is a point on the line and \( (l, m, n) \) are the direction cosines of the line. 2. **Distance Formula**: The distance \( d \) between two points \( (x_1, y_1, z_1) \) and \( (x, y, z) \) is given by the formula: \[ d = \sqrt{(x - x_1)^2 + (y - y_1)^2 + (z - z_1)^2} \] 3. **Substituting the Line Equations**: Substitute \( x, y, z \) from the line equations into the distance formula: \[ d = \sqrt{((x_1 + lr) - x_1)^2 + ((y_1 + mr) - y_1)^2 + ((z_1 + nr) - z_1)^2} \] Simplifying this gives: \[ d = \sqrt{(lr)^2 + (mr)^2 + (nr)^2} \] 4. **Factoring Out \( r^2 \)**: We can factor out \( r^2 \) from the expression: \[ d = \sqrt{r^2(l^2 + m^2 + n^2)} \] This simplifies to: \[ d = r \sqrt{l^2 + m^2 + n^2} \] 5. **Using the Property of Direction Cosines**: Since \( l, m, n \) are direction cosines, we know that: \[ l^2 + m^2 + n^2 = 1 \] Therefore, substituting this into our distance formula gives: \[ d = r \sqrt{1} = r \] 6. **Conclusion**: Since \( r \) represents a distance, it must be non-negative. Thus, the distance \( d \) is equal to \( |r| \), but since \( r \) is a distance, we can conclude: \[ d = r \] ### Final Answer: The distance from the point \( (x_1, y_1, z_1) \) to the point \( (x, y, z) \) on the line is \( r \).
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