Find the (perpendicular) distance from the line given by the parametric equations \[ \begin{array}{l}x(t)=-3-2 t \\ y(t)=3+4 t \\ z(t)=-1-10 t\end{array} \] to the point \( (8,6,-2) \)
Real Tutor Solution
Answer
Solution
Sign in to Unlock Answers for Free!
A Learning Platform Trusted by Millions of Real Students and Teachers.
Reviewed and approved by the UpStudy tutoring team
The Deep Dive
To find the perpendicular distance from the given line to the point \( (8, 6, -2) \), we start by expressing the line in vector form. The direction vector of the line can be derived from the coefficients of \( t \) in the parametric equations: \[ \mathbf{d} = \begin{pmatrix} -2 \\ 4 \\ -10 \end{pmatrix} \] The point on the line at parameter \( t \) is: \[ \mathbf{R}(t) = \begin{pmatrix} -3 \\ 3 \\ -1 \end{pmatrix} + t \begin{pmatrix} -2 \\ 4 \\ -10 \end{pmatrix} = \begin{pmatrix} -3 - 2t \\ 3 + 4t \\ -1 - 10t \end{pmatrix} \] We can express the point \( \mathbf{P} = \begin{pmatrix} 8 \\ 6 \\ -2 \end{pmatrix} \) and find the vector from any point on the line to the point \( P \): \[ \mathbf{PQ}(t) = \mathbf{P} - \mathbf{R}(t) = \begin{pmatrix} 8 \\ 6 \\ -2 \end{pmatrix} - \begin{pmatrix} -3 - 2t \\ 3 + 4t \\ -1 - 10t \end{pmatrix} = \begin{pmatrix} 11 + 2t \\ 3 - 4t \\ 9 - 10t \end{pmatrix} \] We want this vector to be perpendicular to the direction vector \( \mathbf{d} \), which means their dot product is zero: \[ \mathbf{PQ}(t) \cdot \mathbf{d} = (11 + 2t)(-2) + (3 - 4t)(4) + (9 - 10t)(-10) = 0 \] Expanding this: \[ -22 - 4t + 12 - 16t - 90 + 100t = 0 \] Combine like terms: \[ (100t - 20t) + (-22 + 12 - 90) = 0 \implies 80t - 100 = 0 \] \[ 80t = 100 \implies t = \frac{100}{80} = \frac{5}{4} \] Now substitute \( t = \frac{5}{4} \) back into the expression for \( \mathbf{R}(t) \) to find the point on the line: \[ \mathbf{R}\left(\frac{5}{4}\right) = \begin{pmatrix} -3 - 2 \left(\frac{5}{4}\right) \\ 3 + 4 \left(\frac{5}{4}\right) \\ -1 - 10 \left(\frac{5}{4}\right) \end{pmatrix} = \begin{pmatrix} -3 - \frac{10}{4} \\ 3 + 5 \\ -1 - \frac{50}{4} \end{pmatrix} = \begin{pmatrix} -3 - 2.5 \\ 8 \\ -1 - 12.5 \end{pmatrix} = \begin{pmatrix} -5.5 \\ 8 \\ -13.5 \end{pmatrix} \] Next, we find the distance from \( \mathbf{R}\left(\frac{5}{4}\right) \) to \( \mathbf{P} \): \[ \mathbf{D} = \mathbf{P} - \mathbf{R}\left(\frac{5}{4}\right) = \begin{pmatrix} 8 \\ 6 \\ -2 \end{pmatrix} - \begin{pmatrix} -5.5 \\ 8 \\ -13.5 \end{pmatrix} = \begin{pmatrix} 8 + 5.5 \\ 6 - 8 \\ -2 + 13.5 \end{pmatrix} = \begin{pmatrix} 13.5 \\ -2 \\ 11.5 \end{pmatrix} \] Now we calculate the distance using the formula: \[ \text{Distance} = \sqrt{(13.5)^2 + (-2)^2 + (11.5)^2} \] Calculating the components: \[ (13.5)^2 = 182.25, \quad (-2)^2 = 4, \quad (11.5)^2 =