Question

If a unit vector lies in $yz$ plane and makes angles of ${30}^o$ and ${60}^o$ with the positive $y$ axis and $z$ axis respectively, then its components along the co-ordinate axes will be

• A. $\frac{\sqrt{3}}{2},\frac{1}{2},0$
• B. $0,\frac{\sqrt{3}}{2},\frac{1}{2}$
• C. $\frac{\sqrt{3}}{2},0,\frac{1}{2}$
• D. $0,\frac{1}{2},\frac{\sqrt{3}}{2}$

Answer 1

Answer: (B)

$0,\frac{\sqrt{3}}{2},\frac{1}{2}$

As vector lies in $yz$ plane so its $x$ component is zero

$\begin{array}{c}{y}_{component}=\cos {30}^0=\frac{\sqrt{3}}{2}\\ z_{component}=\cos {60}^0=\frac{1}{2}\\ \left(0,\frac{\sqrt{3}}{2},\frac{1}{2}\right)\\ Hence,\\ optionBiscorrectanswer\end{array}$