Arc length or straight distance? (1 Viewer)

[Inexorably Me]

Hey guys (again) is this Q asking for the arc length or straight distance? & how would i do this Q? Please and thank you! you guys are life savers
Q: a sector OAB of a circle centre O, r=20cm, & included angle 2rad is folded to form a cone by placing A against B.
what is the shortest distance from A to B along the surface of the cone?
ans: 19.2

 

[Trebla]

Since it says "along the surface of the cone", I think it's the arc length. You have the answer in front of you, so you should be able to check if it's arc length or not.