1. $\theta_i = 64.12\degree, \theta_j = 150.79\degree, \theta_k = 77.39\degree$
2. a. $-119.98 \hat{\bold{k}}$, b. $-173.2\hat{\bold{k}}$, c. $+ 93.69 \hat{\bold{k}}$, d. $-413.2 \hat{\bold{k}}$, e. $+ 39.93 \hat{\bold{k}}$, f. $-30.09 \hat{\bold{k}}$, g. $+ 149.9 \hat{\bold{k}}$ , h. $0$
3. a. $0$, b. $173,194$, c. $+ 199,993 \hat{\bold{k}}$
4. $\bold{\vec{P}} \cdot \bold{\vec{Q}} = -23$; $\bold{\vec{P}} \cdot \bold{\vec{S}} = -74$; $\bold{\vec{Q}}\cdot \bold{\vec{S}} = 37$.
5. $37\;kN$, $76\degree$
7. $F_{AC} = 169.7 \;lb$; $T_{BC} = 348 \;lb$
9. $F_{AB} = 0$; $F_{AC} = 294.63 \;lb$
11. $101.2\;N\cdot m$
13. $M_A = 400(3) - 400(5) + 300(5) + 200(0.1+0.1) = 740 \;kN\cdot m$
15. $1.5 \;kN \le P \le 9.0\;kN$
16. $a = 25\; mm$
17. a) $ R_A = 3.00 \;lb \;\; M_A = 28.0 lb\cdot pulg$
b) $R_A = 1.80 \;lb \;\; M_A = 8.80 \;lb \cdot pulg$