Question
a cylindrical cup is made so that the sum of its diameter and its height is 25 cm. find the dimensions of the cup so that the surface area of the cup is a maximum. The answers are. D= 50/3. H=25/3. But how do u get that
Answers
Steve
2r+h = 25
a = πr(r+2h) = πr(r+25-2r) = π(25r-3r^2)
da/dr = 0 when r = 25/3
d = 2r = 50/3
h = 25 - 50/3 = 25/3
a = πr(r+2h) = πr(r+25-2r) = π(25r-3r^2)
da/dr = 0 when r = 25/3
d = 2r = 50/3
h = 25 - 50/3 = 25/3