、、 和 是位于一个岛上的四个村庄,其中 位于 的正北方。
,,,。
角 且角 为钝角。

- (a)
证明 位于 的正东方。
答
- (b)
求 相对于 的方位角。
答 ...
- (c)
一位村民以 9.5 km/h 的恒定速度从村庄 慢跑至村庄 ,他走的是最短路线。求该村民从村庄 慢跑至村庄 所用的时间。用分钟和秒表示你的答案,精确到最接近的十秒。
答 ... 分 ... 秒
它不会直接告诉你答案,而是问你卡在哪一步看看 AI 是怎么陪你一步步弄懂这道题的
完整解法
4(a)
1. Calculate the sum of the squares of the two shorter sides of triangle PQR.
2. Calculate the square of the longest side and compare.
Since , by the converse of Pythagoras' theorem, is a right-angled triangle with .
3. Use the bearing information to conclude the relative position of P.
We are given that is due north of , which means the line segment lies on the North-South axis.
Since and from the given layout is to the right of the North-South line , must be due east of .
Since , . As is due north of , is due east of .
4(b)
1. Find angle PRQ using right-angled trigonometry
In , since is due east of and is due north of , .
2. Find the obtuse angle PSR using the Sine Rule
In , using the Sine Rule:
Since is obtuse:
3. Find angle PRS
Using the sum of angles in :
4. Calculate the bearing of S from R
Since is due north of , the bearing of from is the angle .
Bearing (to 1 d.p.)
4(c)
1. Find angle $PRS$ using the sine rule in triangle $PRS$.
Using the sine rule in :
Since is obtuse:
2. Find angle $QRS$ by adding angle $PRQ$ and angle $PRS$.
In right-angled (since is due east of and is due north of ):
3. Calculate the distance $QS$ using the cosine rule in triangle $QRS$.
Using the cosine rule in :
4. Calculate the time taken to jog from $Q$ to $S$ and round to the nearest ten seconds.
Speed
Time taken
Correct to the nearest ten seconds, the time is .
5 min 20 s
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