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Select the correct answer.

Vector [tex]$v$[/tex] has its initial point at [tex]$(7, -9)$[/tex] and its terminal point at [tex][tex]$(-17, 4)$[/tex][/tex]. Which unit vector is in the same direction as [tex]$v$[/tex]?

A. [tex]$u =\left\langle\frac{-24}{\sqrt{745}}, \frac{-13}{\sqrt{745}}\right\rangle$[/tex]

B. [tex][tex]$u =\left\langle\frac{-24}{\sqrt{725}}, \frac{13}{\sqrt{725}}\right\rangle$[/tex][/tex]

C. [tex]$u =\left\langle\frac{-24}{\sqrt{745}}, \frac{13}{\sqrt{745}}\right\rangle$[/tex]

D. [tex]$u =\left\langle\frac{24}{\sqrt{725}}, \frac{-13}{\sqrt{725}}\right\rangle$[/tex]


Sagot :

To find the unit vector in the same direction as vector [tex]\( v \)[/tex] from initial point [tex]\((7, -9)\)[/tex] to terminal point [tex]\((-17, 4)\)[/tex], we follow these steps:

1. Calculate the components of the vector [tex]\( v \)[/tex]:
[tex]\[ v_x = x_{\text{terminal}} - x_{\text{initial}} = -17 - 7 = -24 \][/tex]
[tex]\[ v_y = y_{\text{terminal}} - y_{\text{initial}} = 4 - (-9) = 13 \][/tex]

So, the vector [tex]\( v \)[/tex] is [tex]\((-24, 13)\)[/tex].

2. Calculate the magnitude of vector [tex]\( v \)[/tex]:
[tex]\[ \|v\| = \sqrt{v_x^2 + v_y^2} = \sqrt{(-24)^2 + 13^2} = \sqrt{576 + 169} = \sqrt{745} \][/tex]

3. Calculate the components of the unit vector [tex]\( u \)[/tex]:
[tex]\[ u_x = \frac{v_x}{\|v\|} = \frac{-24}{\sqrt{745}} \][/tex]
[tex]\[ u_y = \frac{v_y}{\|v\|} = \frac{13}{\sqrt{745}} \][/tex]

Thus, the unit vector [tex]\( u \)[/tex] in the same direction as [tex]\( v \)[/tex] is:
[tex]\[ u = \left\langle \frac{-24}{\sqrt{745}}, \frac{13}{\sqrt{745}} \right\rangle \][/tex]

Therefore, the correct answer is:
[tex]\[ \boxed{C. \quad u = \left\langle \frac{-24}{\sqrt{745}}, \frac{13}{\sqrt{745}} \right\rangle} \][/tex]