# Homework Help: Vectors and displacement.

1. Jan 16, 2010

### sneeterpop

1. The problem statement, all variables and given/known data
A map suggests that Atlanta is 728 mi in a direction of 4.80° north of east from Dallas. The same map shows that Chicago is 561 miles in a direction of 20.8° west of north from Atlanta. Modeling the Earth as flat, use this information to find the displacement from Dallas to Chicago.

magnitude _______Miles
2. Relevant equations

R = Sqrt (A^2+B^2 - 2(A)(B)(cos(theta)))

3. The attempt at a solution

I ended up getting 817 as my answer, the site kept saying its within 10% of the correct answer, but I may have rounded wrong. I didn't round until the very last part.

2. Jan 16, 2010

### payumooli

resolve them into two vectors
finally take the magnitude of the vector

i get an answer way off yours

3. Jan 17, 2010

### Redbelly98

Staff Emeritus
That equation should work. I used it and got a different answer, but within 10% of yours.

What are you using for theta?

4. Jan 19, 2010