<p>The volume of the right cylinder is (3.14)r^2h = 169.76</p>
<p>Now, draw a circle. </p>
<p>Your circle represents the top of the cylinder. You are looking down on the top of the cylinder.</p>
<p>Inscribe the biggest square that you can inside that circle.</p>
<p>Draw a triangle that includes the center and two of the four corners of the circle.</p>
<p>This is a right, isoceles triangle. Each of the two equal sides is equal to 3, the radius.</p>
<p>By the Pythagorean Theorem, the hypotenuse of your triangle is 3 (2^(1/2)).</p>
<p>The length of that hypotenuse, 3 (2^(1/2)), is the greatest possible length (and width, we are talking about a square) in the proposed square prism. </p>
<p>Of course, the height of the proposed square prism is 6, the height of the cylinder.</p>
<p>The volume of the square prism will be, of course, l x w x h.</p>
<p>Length is 3 (2^(1/2))
Width is also 3(2^(1/2))
Height is 6.</p>
<p>Volume of the inscribed square prism is lwh, which is, skipping a few steps, (6)(9)(2)=108.</p>
<p>The target answer is then 169.76 - 108 = (approx) 61.6.</p>