### Home > CALC > Chapter 4 > Lesson 4.1.1 > Problem 4-12

Khi thinks that when the flags below are rotated, the (volume of )

*)*

*)).*

Decide if he is correct. If he is incorrect, explain the error in his logic.

Start by visualizing the terms in Khi's equation: What does Volume and Volume

*look like? What does Volume (*

*) look like?*

Volume is cone with radius

*is a cylinder with radius*

*[cone with*

*] + [cylinder with*

*]*

Try computing the volume of each:

Volume Volume

*cone*

Volume

Evaluate and compare.

Volume () is a single 3D solid that looks like a cone with its top cut off. To compute its volume, it must be dissected into pieces:

*[large cone with*

*]*

*]*

Use the eTool below to visualize this problem.

Click on the link to the right to view the full version of the eTool: *Calc 4-12 eTool*