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Find a vector equation and parametric equations for the line segment that joins p to q.P(0, - 1, 1), Q(1/2, 1/3, 1/4)

User Rnn
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1 Answer

3 votes

Answer:

vector equation:


\overrightarrow{PQ}=\begin{bmatrix}1/2}\\4/3\\-3/4\end{bmatrix}

parametric equations:


r_x = (1)/(2)t\\r_y = -1 +(4)/(3)t\\r_z = 1=(3)/(4)t

Explanation:

The coordinates of the points are given as:

P(0,-1,1) and Q(1/2,1/3,1/4)

the coordinates of any points are also position vectors (vectors starting from the origin to that point), and can be represented as:


\overrightarrow{OP} = 0\hat{i}-1\hat{j}+1\hat{k}

or


\overrightarrow{OP} = \begin{bmatrix}0\\-1\\1\end{bmatrix}

similarly,


\overrightarrow{OQ} =(1)/(2)\hat{i}+(1)/(3)\hat{j}+(1)/(4)\hat{k}

or


\overrightarrow{OQ} = \begin{bmatrix}1/2}\\1/3\\1/4\end{bmatrix}

the vector PQ can be described as:


\overrightarrow{PQ}=\overrightarrow{OQ}-\overrightarrow{OP}


\overrightarrow{PQ}=\begin{bmatrix}1/2}\\1/3\\1/4\end{bmatrix}-\begin{bmatrix}0\\-1\\1\end{bmatrix}


\overrightarrow{PQ}=\begin{bmatrix}1/2}\\4/3\\-3/4\end{bmatrix}

this is the vector equation of the line segment from P to Q.

to make the parametric equations:

we know that the general equation of a line is represented as:


\overrightarrow{r} = \overrightarrow{r_0} + t\overrightarrow{d}

here,
\overrightarrow{r_0}: is the initial position or the starting point. in our case it is the position vector of P

and
\overrightarrow{d}: is the direction vector or the direction of the line. in our case that's PQ vector.


\overrightarrow{r} = \begin{bmatrix}0\\-1\\1\end{bmatrix} + t\begin{bmatrix}1/2}\\4/3\\-3/4\end{bmatrix}

that parametric equations can now be easily formed:


\begin{bmatrix}r_x\\r_y\\r_z\end{bmatrix} = \begin{bmatrix}0\\-1\\1\end{bmatrix} + t\begin{bmatrix}1/2}\\4/3\\-3/4\end{bmatrix}


r_x = (1)/(2)t\\r_y = -1 +(4)/(3)t\\r_z = 1=(3)/(4)t

these are the parametric equations of the line PQ

User Davidjnelson
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