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

## 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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Simon Bridge
Homework Helper
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:
SteamKing
Staff Emeritus