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[/I]The second question talks about finding the right direction to move in.

2) A man wished to row across a lake to a point directly south of him. If the lake has a current flowing west at 3km/hr and he can row at 7km/hr, find the direction in which he must row.

Draw a rough sketch: You'll get a right triangle with one leg pointing South and one leg pointing because the man has to componsate the current running West. The course is described by the hypotenuse. Use the Sine function to calculate the angle of deviation from South.
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The fourth question was about vector products, which I'm pretty sure I have a good grasp on. Still, an elaboration on how to work them out would be nice, just so I can be sure I've done it right.

4) Find the vector product:

*(2i - j)* x

*(6i + 3j + 2k)*

I've got:

[I]let a = 2i = j, b = 6i + 3j + 2k

a * b =

| i j k |

| 2

**-**1 0|

<<<<<< there is a negative sign missing
|6 3 2|

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=

i( (

**-**1)(2) - (0)(3) ) - j( (2)(2) - (0)(6) ) + k( (2)(3) - (

**-**1)(6) )

**= -2i - 4j + 12k**
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