Terminology Question (drawing a vector triangle)

  • Thread starter DLxX
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  • #1
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Im getting questions wrong because of the way the questions are written.

How do you draw the vectors when the question says 30 degrees west of north? Like the picture attached?

Btw dont mind the filename I named it incorrectly.
 

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Answers and Replies

  • #2
Moonbear
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Science Advisor
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Well, the attachment isn't approved yet, so I can't look at your picture, but I can explain it in words for you. In your example, 30 degrees west of north, you start with north. Then go 30 degrees west of that. If you think of north as 12 on a clock, 30 degrees west of north puts you at 11:00.
 
  • #3
BobG
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They are giving you a principal direction and orienting the vector relative to your principle direction.

In this case your principle direction is North (0 or 360 degrees). You're 30 degrees West of North, so you're moving counter clockwise. That's -30 degrees relative to North. That makes your direction 330 degrees.

Another example: 40 degrees South of East. East is your principle direction (90 degrees). You're 40 degrees South of your principal direction. Going from East to South is clockwise or positive. That's +40 degrees to your 90 degrees, or 130 degrees.

In other words, turn your principal direction into degrees (0/360 for North, 90 for East, 180 for South, 270 for West).

Figure out if your secondary direction is clockwise (positive) or counter-clockwise (negative) relative to your principal direction.

Add to your prinicipal direction (keeping in mind adding a negative number is the same as subtraction).
 

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