1. The problem statement, all variables and given/known data Find the distance from Atlanta to San Francisco if Atlanta is @ 33.75°N and 84.40°W and San Francisco is @ 37.78°N and 122.42°W. Explain your strategy. 2. Relevant equations cos phi = z/rho cos theta = x/r r = rho*sin phi 3. The attempt at a solution I believe that latitudes are my thetas and the longitudes are my phis. I've tried to come up with equations that allow me to solve for a single variable but I keep having too many unknowns. Someone suggested use the difference in theta (and phi) in my equations but even then I am still stuck on how to convert these angle measures into spherical coords. I am looking for a way to get started, and any help would be greatly appreciated.