you can imagine it like this: imagine you take a sheet of paper and roll it into a tube the lateral aera=circumference times height because if yo open the paper, the area is legnth times width, and when you roll it up, width turns into circumference
so
LA=h(circumference0 LA=h2pir LA=18*2*pi*6 LA=216pi pi=3.14 for this question LA=678.24