Westonci.ca offers quick and accurate answers to your questions. Join our community and get the insights you need today. Explore in-depth answers to your questions from a knowledgeable community of experts across different fields. Get quick and reliable solutions to your questions from a community of experienced experts on our platform.

13 of 20 QID: 26864 What is the radius of a right circular cylinder with a volume of 12 in3 if it has a minimum surface area

Sagot :

Answer:

r = 1,248 in

Step-by-step explanation:

v(c) = 12 in³

The surface area of a right cylinder is:

Area of the base and top  + lateral area

S(a)  =  2*π*r²  + 2*π*r*h   (1)

v(c) = 12 in³  =  π*r²*h        h is the height of the cylinder, then

h  =  12 / π*r²

By substitution,  in equation (1) we get  the  Surface area as a function of r

S(r)  =  2*π*r² +   2*π*r*  ( 12 / π*r²)

S(r)  =  2*π*r² + 24 /r

Tacking derivatives on both sides of the equation we get:

S´(r)  =  4*π*r -  24 /r²

S´(r)  = 0            4*π*r -  24 /r²  =  0       π*r - 6/r² = 0

 π*r³ - 6  = 0

r³   =  1,91    

r = 1,248 in    

How do we know that the value  r  =  1,248 makes  Surface area minimum??

We get the second derivative

S´´(r)  =  4*π  +  48/r³    S´´(r)  will be always positive therefore we have a minumum of S   at the value of   r = 1,248 in

           

Thank you for your visit. We're dedicated to helping you find the information you need, whenever you need it. We appreciate your time. Please revisit us for more reliable answers to any questions you may have. Keep exploring Westonci.ca for more insightful answers to your questions. We're here to help.