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If $\mathbf{A}=\langle 3,4,0\rangle$, then the unit vector in the direction of $\mathbf{A}$ is
A$\langle 3,4,0\rangle$
B$\left\langle \frac{3}{5},\frac{4}{5},0\right\rangle$
C$\left\langle \frac{5}{3},\frac{5}{4},0\right\rangle$
D$\left\langle \frac{1}{3},\frac{1}{4},0\right\rangle$
Answer & Solution
Correct answer: B. $\left\langle \frac{3}{5},\frac{4}{5},0\right\rangle$
A unit vector is $\hat{\mathbf{A}}=\mathbf{A}/\|\mathbf{A}\|$. Here $\|\mathbf{A}\|=\sqrt{3^2+4^2}=5$, so $\hat{\mathbf{A}}=\left\langle \frac{3}{5},\frac{4}{5},0\right\rangle$.
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