3-2 할리데이 10판 솔루션 일반물리학

$$\begin{cases} \vec r:(12\ut{m},30^\circ)\\ \vec r =r_x \hat i+ r_y \hat j\\ \end{cases} $$
(a)$r_x=?$ $$ \begin{aligned} r_x&=r\cos\theta\\ &=12\cos30^\circ\ut{m}\\ &=6\sqrt{3}\ut{m} \end{aligned} $$
(a)$r_y=?$ $$ \begin{aligned} r_x&=r\sin\theta\\ &=12\sin30^\circ\ut{m}\\ &=6\ut{m} \end{aligned} $$