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## Homework Statement

A canoeist wants to travel straight across a river that is 0.10km wide. However, there is a strong current moving downstream with a velocity of 3.0km/h. The canoeist can maintain a velocity relative to the water of 4.0km/h.

a) In what direction should the canoeist head to arrive at a position on the other shore directly opposite to his starting position?

b) How long with the trip take him?

## Homework Equations

a

^{2}+ b

^{2}= c

^{2}

sin a = (sin b/b) X a

cos θ = adjacent/hypotenuse

## The Attempt at a Solution

a) r

^{2}= 4

^{2}+ 3

^{2}= 25

r = 5km

sin θ = (sin90/5)X 3

sin θ = 0.6

θ = 37

He should aim 37° upstream, from the destination reference.

The book's answer is: He should aim upstream at an angle 41° with respect to the riverbank.

b) cos 37 = 0.1/hyp

hyp = 0.1/0.79

hyp = 0.125

0.125/4 = 0.03 = 1.9min

The book's answer is 2.3 min.

Any help that you can provide is greatly appreciated!