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What are the magnitude and direction?

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    What are the magnitude and direction?

    If a = (5, -12), what are the magnitude and direction of a?


    The above question marked me wrong I answered:
    (13, 292.6)

    I double checked this online and my answer was correct

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  3. Uguessus is offline Junior Member Pro Subscriber
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    Quote Originally Posted by csabin View Post
    If a = (5, -12), what are the magnitude and direction of a?


    The above question marked me wrong I answered:
    (13, 292.6)

    I double checked this online and my answer was correct
    I calculated (13, 337deg). Here is what I have for the angle...270deg + 67deg = 337deg.

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  5. csabin is offline Junior Member
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    Quote Originally Posted by Uguessus View Post
    I calculated (13, 337deg). Here is what I have for the angle...270deg + 67deg = 337deg.

    I even went back to a calculator website. The angle should be 360-67.3 = 292.7 degrees because if you think of this even logically the vector would have to be closer to the y axis much closer to 270 degrees. Due to the fact that -12 is much larger then 5.

    Also you can even prove this with a calculation arctan(-12/5) = -67.3 degrees. Im 1000% positive this is an error on test guide or I have wrote the problem wrong.

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  7. Uguessus is offline Junior Member Pro Subscriber
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    You are right. I made a big mistake on where I should add or deduct the 67deg, 292Deg is right.

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    Kalbi_Rob is offline Experienced Member
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    Quote Originally Posted by Uguessus View Post
    You are right. I made a big mistake on where I should add or deduct the 67deg, 292Deg is right.
    Always make a visual verification that you are in the right quadrant using the (X,Y) as a basis for your final answer.

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  11. Uguessus is offline Junior Member Pro Subscriber
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    Quote Originally Posted by Kalbi_Rob View Post
    Always make a visual verification that you are in the right quadrant using the (X,Y) as a basis for your final answer.
    That's a good point. Thanks.

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    Update Question Please

    Any way the moderators may be able to update this question to the correct answer? I also got it marked wrong, and came up with the same answer deemed correct in this forum topic.

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    Quote Originally Posted by bob152637485 View Post
    Any way the moderators may be able to update this question to the correct answer? I also got it marked wrong, and came up with the same answer deemed correct in this forum topic.
    Thanks for reporting, someone will take a look.

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