1. The problem statement, all variables and given/known data 3. The attempt at a solution Honestly I'm completely lost, this is an assignment for my calc 3 class. I tried to do (a) but I think I'm completely off track so any helps appreciated. r x a=0 |r x a|=0=|r||a|sin(theta) r cannot be 0 since it's in the denominator Assuming neither G nor M is 0, a cannot be 0 so theta must be 0 or 180 |r||a|sin(0)=0 |r||a|sin(180)=0 the above is my attempt at (a) I haven't tried any others yet :(.