Question

英文的应用题！求帮忙解答！在线等！！！十万火急啊

Maya is 6 km offshore on a boat at point B and wishes to reach a coastal village
which is 4 km down the straight shoreline at point D from the point A on the shore
nearest to the boat.（就这句不明白，什么叫，她在距离海岸6km的船上记做b点，她想要到大距离船最近的海岸a点沿着海岸线向下4km的村庄记做d点， 我翻译的把我给绕进去了！压根没明白这几个点的位置关系。。T T) She can row at 5 km/hour and run 7 km/hour. Point C is where she should land her boat to reach the village in the least amount of time.

a) Draw a labeled diagram for this problem, which includes points A, B, C, and D.
Let x be the distance between points A and C.
帮忙翻译一下题目，我就是读不明白这个人的位置究竟在哪还有那条海岸线在哪？？
这个图的位置大概是什么样子的？？？
b) What two assumptions should you make about the wind and the water?

c) State the following quantities:
running distance = running time =
rowing distance = rowing time =
d) How far away is point C from point A accurate to 2 decimal places?

谢谢！！
很着急的！！谢谢

Answer 1

AD=4km  AB=6km

设船靠岸的点C距离AC=x。

BC=√(6^2+x^2)

CD=4-x

用时：T=BC/5+CD/7=√(6^2+x^2)/5+(4-x)/7

                                 =[7√(6^2+x^2)-5x]/35 +4/7

设y=7√(6^2+x^2)-5x >7x-5x=2x

函数y随着x增加而递增，

因此x=0时，用时最短T=6/5+4/7=62/35

Answer 2

看图