I've given you the formula to solve for each problem, so you should be able to do it now. Good luck !!
Ive showed you how to do problems 1 & 4, so you know how to do it
Answer for #1 is 14[tex] \pi [/tex] cm
Answer for #4 is 50[tex] \pi [/tex] /3 cm or 52.35 cm (if you want to put it in fraction form)