Vector addition and subtraction. feeling stupid for being confused over this

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SUMMARY

The discussion centers on vector addition and subtraction using the vectors A = 2i + 3j and B = -5i + 6j. The correct results for A + B and A - B are determined to be -3i + 9j and 7i - 3j, respectively. Participants clarify that while angles can be used for calculations, the Cartesian representation is sufficient and often simpler. Drawing a vector diagram is recommended to visualize the addition and subtraction of vectors accurately.

PREREQUISITES
  • Understanding of Cartesian coordinates and vector representation
  • Basic knowledge of vector addition and subtraction
  • Familiarity with polar and Cartesian coordinate conversions
  • Ability to interpret vector diagrams
NEXT STEPS
  • Learn how to convert between Cartesian and polar coordinates
  • Study vector diagram techniques for visualizing vector operations
  • Explore advanced vector operations, including dot and cross products
  • Practice problems involving vector addition and subtraction in different quadrants
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Students in physics or mathematics, educators teaching vector concepts, and anyone seeking to improve their understanding of vector operations in Cartesian coordinates.

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Homework Statement



A = 2i + 3j
B = -5i + 6j

Calculate (draw vector diagram)
A + B
A - B

Homework Equations



actually we're just confused as to whether we need to use the angles to answer this or just answer it directly, meaning that for A + B the answer would be -3i + 9j

The Attempt at a Solution



do we use

A + B = -3i + 9j

or solve for the angles(*rounded off) and use

A+B = ((√13)cos56 + (√61)cos50)i + ((√13)sin56 + (√61)sin50)j

?
 
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Try drawing the vectors on graph paper, and adding/subtracting head-to-tail.
They are simple enough to do this, and it will clear up your confusion.

The vectors are provided to you in Cartesian representation. If you do it by angles, you want the polar representation. These are entirely equivalent and will get you the same answers. (provided you worked out the angles correctly - yours are all in the 1st quadrant but the vectors are not... one is in the 4th quadrant so it's angle is greater than 270 degrees - I have not checked that you've accounted for this.)
 
Last edited:
The problem statement asks you to 'draw vector diagram' for A+B and A-B. Did you do that?
 

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