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

AI Thread Summary
Vector addition and subtraction can be performed directly using Cartesian coordinates without needing to convert to angles. For the vectors A = 2i + 3j and B = -5i + 6j, the sum A + B results in -3i + 9j, while A - B yields 7i - 3j. Drawing the vectors on graph paper can help clarify the addition and subtraction process visually. Although polar representation can be used, it is not necessary for this problem, and accuracy in angle calculation is crucial if chosen. The problem specifically requests a vector diagram for both A + B and A - B, which should be completed for better understanding.
mathkillsalot
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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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