Question 5.] (It) marks} Let S be the last nanzerc digit of year student number. Suppose you want to malte a cup from aluminium sheet. Yeur cup is cylindrical in shape+ with radius r and height hr has no lid, and needs to hold see + 10 x S m] at" water. [a]: Express the outer surface area A of your cup in terms 01' r only. [11} Find the critical paint of A and determine the surface area af the cup at the critical paint. {c} Use the second derivative test tn shew that the surface area has a minimtun at the critical point