[填空题]
Jack sets out for a horsvih; be)g8h 0.l.z feke ride from his family ran:rgp0 g mntvrp ,2k1:tch at point $\mathrm{A} $. He rides at an average speed of 6.3$ \mathrm{~km} / \mathrm{h} $ for 28 minutes, on a bearing of $40^{\circ}$ from the ranch, until he stops for a break near a spring at point B.
1. Find the distance from point $\mathrm{A}$ to point $\mathrm{B}$ .
$\text { Jack leaves point } \mathrm{B} \text { on a bearing of } 112^{\circ} \text { and continues to ride for a distance of } 5.8 \mathrm{~km} \text { until he reaches a river at point } \mathrm{C} \text {. }$
2. 1. Show that $A \hat{B}$ C is $108^{\circ}$ .
2. Find the distance from point A to point C . ≈
3. Find BĈA.
Jack's brother John wants to ride a horse directly from the ranch to meet Jack at point $\mathrm{C} $.
4. Find the bearing that John must take to point $\mathrm{C} $.
John rides at an average speed of 12.9 $\mathrm{~km} / \mathrm{h}$ .
5. Find, to the nearest minute, the time it takes for John to reach point $\mathrm{C}$ .≈ minutes
