1. The problem statement, all variables and given/known data I don't know if 'hops' is the correct English term, but that's the term my assignment uses in Dutch. The assignment is about the reflection of radiowaves by the f1-layer in the atmosphere and a hop is defined as one such reflection. The question is, what is the minimum amount of hops needed for a radiowave to travel from Amsterdam to Tokyo? We have to use Mathematica to solve it. 2. Relevant equations First of all we have to calculate the spherical distance from Amsterdam to Tokyo. I calculated this to be 9293.71 km. Then we have to calculate the angle between Amsterdam and Tokyo, as seen from the centre of the earth, in radians, which I found to be 2.3541. 3. The attempt at a solution I'm pretty much at a loss now, how do I continue?