3-34 할리데이 11판 솔루션 일반물리학

$$ \begin{cases} \vec d_1+\vec d_2&=6\vec d_3\\ \vec d_1-\vec d_2&=4\vec d_3\\ \vec d_3&=3\i+5\j\\ \end{cases} $$ $$ \begin{cases} \vec d_1&=5\vec d_3\\ \vec d_2&=\vec d_3\\ \end{cases} $$ $$\ab{a}$$ $$ \begin{aligned} \vec d_1&=5\vec d_3\\ &=5\(3\i+5\j\)\\ &=15\i+25\j\\ \end{aligned} $$ $$\ab{b}$$ $$ \begin{aligned} \vec d_2&=\vec d_3\\ &=3\i+5\j\\ \end{aligned} $$