12-32 할리데이 11판 솔루션 일반물리학

$$\begin{cases} \vec F_1&=8.40\i-5.70\j\ut{N}\\ \vec F_2&=16.0\i+4.10\j\ut{N}\\ \end{cases}$$ $$\ab{a,b}$$ $$\begin{aligned} \vec F_3&=-\br{\vec F_1+\vec F_2}\\ &=-24.4\i+1.6\j\ut{N}\\ \end{aligned}$$ $$\begin{cases} F_{3x}&=-24.4\ut{N}\\ F_{3y}&=1.6\ut{N}\\ \end{cases}$$ $$\ab{c}$$ $$\begin{aligned} \theta&=\tan^{-1}{1.6\over-24.4}\\ &\approx 3.0761126286663285\ut{rad}\\ &\approx 3.08\ut{rad}\\ \end{aligned}$$