Vektor 2 Dimensi
Diketahui vektor posisi \(\overrightarrow{\text{OP}}= \textbf{p} = \left(\begin{array}{c}x_1\\ y_1\end{array}\right)\) Panjang vektor tersebut dinyatakan dengan \(||\textbf{p}|| = \sqrt{x^2_1 + y^2_1}\)Vektor 3 Dimensi
Diketahui vektor posisi \(\overrightarrow{\text{OQ}}=\textbf{q} = \left(\begin{array}{c}x_1\\ y_1\\z_1\end{array}\right)\) Panjang vektor tersebut dinyatakan dengan \(||\textbf{q}|| = \sqrt{x^2_1 + y^2_1 + z^2_1}\)Panjang Vektor \(\overrightarrow{\text{PQ}}\)
Jika \(\textbf{p} = \left(\begin{array}{c}x_1\\ y_1\end{array}\right)\) dan \(\textbf{q} = \left(\begin{array}{c}x_2\\ y_2\end{array}\right)\), maka \(\overrightarrow{\text{PQ}} = \textbf{q}\:-\: \textbf{p} = \left(\begin{array}{c}x_2\:-\:x_1\\ y_2\:-\:y_1\end{array}\right)\) Panjang vektor PQ dapat dihitung sebagai berikut: \(||\overrightarrow{\text{PQ}}|| = \sqrt{(x_2\:-\:x_1)^2 + (y_2 \:-\:y_1)^2}\)Contoh Soal
Soal 1 Tentukan panjang vektor \(\textbf{r} = \left(\begin{array}{c}-6\\ 8\end{array}\right)\)
\(||\textbf{r}|| = \sqrt{(-6)^2 + (8)^2}\)
\(||\textbf{r}|| = \sqrt{36 + 64}\)
\(||\textbf{r}|| = \sqrt{100}\)
\(||\textbf{r}|| = 10\)
Jadi panjang vektor posisi r adalah 10 satuan
Soal 2
Tentukan panjang vektor \(\textbf{p} = \left(\begin{array}{c}1\\ -2\\2\end{array}\right)\)
\(||\textbf{p}|| = \sqrt{1^2 + (-2)^2 + 2^2}\)
\(||\textbf{p}|| = \sqrt{1 + 4 + 4}\)
\(||\textbf{p}|| = \sqrt{9}\)
\(||\textbf{p}|| = 3\)
Jadi panjang vektor posisi p adalah 3 satuan
Soal 3
Diketahui vektor posisi \(\textbf{p} = \left(\begin{array}{c}3\\ 5\\-1\end{array}\right)\) dan \(\textbf{q} = \left(\begin{array}{c}-2\\ 6\\2\end{array}\right)\). Tentukan \(||\overrightarrow{\text{PQ}}||\).
\(\overrightarrow{\text{PQ}} = \textbf{q}\:-\:\textbf{p}\)
\(\overrightarrow{\text{PQ}} = \left(\begin{array}{c}-2\\ 6\\2\end{array}\right)\:-\:\left(\begin{array}{c}3\\ 5\\-1\end{array}\right)\)
\(\overrightarrow{\text{PQ}} = \left(\begin{array}{c}-2-3\\ 6-5\\2-(-1)\end{array}\right)\)
\(\overrightarrow{\text{PQ}} = \left(\begin{array}{c}-5\\ 1\\3\end{array}\right)\)
\(||\overrightarrow{\text{PQ}}|| = \sqrt{(-5)^2 + 1^2 + 3^2}\)
\(||\overrightarrow{\text{PQ}}|| = \sqrt{25 + 1 + 9}\)
\(||\overrightarrow{\text{PQ}}|| = \sqrt{35}\)
Jadi panjang vektor PQ adalah \(\sqrt{35}\) satuan