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What is the direction, in degrees and to 2 decimal places, for the vector whose column form is \[ \begin{pmatrix} a & b \end{pmatrix} \] where $a = 19$ and $b = -5$? Do not give any units in your answer. Your answer must be between $-90°$ and $270°$.

I got the answer as $-75.26°$. I used

\[ \arctan \frac{19}{-5}\]

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    Is this a question? It also sounds like a homework issue.2012-09-11
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    it is @kcrisman ! ;)2012-09-11

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Draw a picture, perhaps more or less to scale. Note that the slope is "rise" divided by "run". Or, in symbols, the slope is the change in $y$ divided by the change in $x$.

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    haha i did and i got the answer so just verifying if it is correct tks2012-09-11
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    @JackyBoi: Do the picture as I suggested. Your answer is not correct. Picture will show that. Your expression is upside down.2012-09-11
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    any example? cause my textbook doesnot have such slope and rise concept perhaps i will learn.. tks2012-09-11
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    @JackyBoi: Change the problem slightly to $a=19$, $b=5$. The slope is $\frac{5}{19}$: the tangent of the angle is opposite divided by adjacent. For your problem, you will want $\arctan(-5/19)$.2012-09-11
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    so -14.74? is that the answer?2012-09-12
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    Sorry, busy. Yes, that's it.2012-09-12
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    ah ok but still thiking how u deduce it as slope and rise cocept.. intresting take on the question2012-09-12