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## Homework Statement

Vector A=(oi +3j), B=(8i-1j), C=(-8i+5j)

Find the angle from the positive x-axis of the vector A+B+C

Find the magnitude and direction of the vector -A-B+C

## Homework Equations

## The Attempt at a Solution

I know that the answer is 90, but I'm not sure how to get that. I know that theta=tan-1(y/x) and that doesn't equal 90.

As far as the second part, this is what I did:

square root (0-8-8)^2+(-3+1+5)^2 and that supposed to be equal to 16.28, but it's not. Would I use tangent to find the angle?

Could someone please show me how to do this?

Thank you very much