Question

a fishing boat is anchored 9 km away from the nearest point on the shore. A messenger must be sent from the fishing boat to a camp, 15 km from the point on the shore closest to boat. if the messenger can walk at a speed of 5 km/he and can row at 4 km/hr, determine the distance of that point (in km) from the shore, where he must land so as to reach the shore in least possible time.

Answer 1

not sure of the answer

Answer 2

Answer: 3 km

Distance is a scalar measure of the interval between two locations measured along the actual path connecting them.

Here,

Given:

• c = 15 km

• d = 9 km

• u = 5 km/h

• v = 4 km/h

                                $sec\alpha =ratio\quad of\quad speed\quad of\quad walking\quad and\quad rowing \\= \frac{5}{4} \\= 1.25$

                                $cot \alpha = 1.33$

                                $D=c-d\quad cot\alpha\\=15-(9\times 1.33) =3km$