Problem 6.2.2
Here are the pictures I tried to draw on the board.

Ignore all the technical looking stuff in boldface ( Mathematica commands) and just look at the pictures and other text.The red rectangle will be the base of the "square" perpendicular to the x-axis.

[Graphics:6-2-2.txtgr2.gif][Graphics:6-2-2.txtgr1.gif]

[Graphics:6-2-2.txtgr2.gif][Graphics:6-2-2.txtgr3.gif]
[Graphics:6-2-2.txtgr2.gif][Graphics:6-2-2.txtgr4.gif] 

[Graphics:6-2-2.txtgr2.gif][Graphics:6-2-2.txtgr5.gif]

Here is a 3-D view of the square cross-section.

[Graphics:6-2-2.txtgr2.gif][Graphics:6-2-2.txtgr6.gif]
[Graphics:6-2-2.txtgr2.gif][Graphics:6-2-2.txtgr7.gif]

Here's a bunch of 'em.

[Graphics:6-2-2.txtgr2.gif][Graphics:6-2-2.txtgr8.gif]
[Graphics:6-2-2.txtgr2.gif][Graphics:6-2-2.txtgr9.gif]

A view from the other side:

[Graphics:6-2-2.txtgr2.gif][Graphics:6-2-2.txtgr10.gif]
[Graphics:6-2-2.txtgr2.gif][Graphics:6-2-2.txtgr11.gif]