Using Shell method to solve Disk method Problem

[barapapupi]

Homework Statement

Use the shell method to find the volume of the area enclosed by:

$y= 16-x^2$ , $y= 16$,$x=4$, around $y=16$

Homework Equations

$$2\pi\int (shell height)( shell radius)$$

The Attempt at a Solution

I tried using the disk method and obtained $$\frac{1024}{5}*\pi$$

but I'm having trouble because they as to specifically use the shell method and so far I think the $$shell height = 5 - \sqrt{25-y}$$ , but I have no idea how to get the radius, and is the integration on y=0 to y=25?

EDIT: Nevermind, I found the answer

 

[Asim Riaz]

. The radius would be the same as the circle that is generated when y=16. Thus, the radius = 4 and the integration would be from y=0 to y=16. 2\pi\int_{0}^{16} (16-y)(4) dy 2\pi\int_{0}^{16} 64-4y dy 2\pi[64y-2y^2]_0^16 2\pi(1024-128) 2\pi*896 = 5632\pi