What is the displacement from Dallas to Chicago using a flat Earth model?

[sneeterpop]

Homework Statement

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

Homework Equations

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

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.

 

[payumooli]

resolve them into two vectors
then use vector addition
finally take the magnitude of the vector

i get an answer way off yours

 

[Redbelly98]

Homework Equations

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

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.

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

What are you using for theta?

 

[payumooli]

i didnt use your formula
and the formula you are trying to use is not right
it should be
R = Sqrt (A^2+B^2 + 2(A)(B)(cos(theta)))