the unit vector, or a vector on the Unit Circle, has a magnitude of 1, thus is called a Unit vector :), in the Unit Circle, and is coterminal with hmm in this case -6,-8, which has a bigger magnitude than 1
[tex]\bf \begin{array}{ccccllll}
\ \textless \ &-6&,&-8\ \textgreater \ \\
&a&&b
\end{array}\qquad \textit{so the vector }v\textit{ magnitude is}
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||v||=\sqrt{a^2+b^2}\implies ||v||=\sqrt{(-6)^2+(-8)^2}\implies ||v||=10
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\textit{thus the unit vector }v_o\textit{ will be}\implies \left(\frac{a}{||v||}, \frac{b}{||v||} \right)
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or\implies \left( \frac{-6}{10},\frac{-8}{10} \right)\implies \left( \frac{-3}{5},\frac{-4}{5} \right)[/tex]