<li><p>If the portion of the graph of x^2 + y^2 = 4 that lies in quadrant I is revolved around the x-axis, the volume of the resulting figure is
answer 16.8</p></li>
<li><p>A right circular cone whose base radius is 12 is inscribed in a sphere of radius 13. What is the volume of the cone?
a) 720
b) 2197pi/3
c) 864
d) 1440
e) 2592
answer is 864</p></li>
<li><p>Given a right circular cylinder such that the volume has the same numerical value as the total surgace area. The smallest integral value for the radius of the cylinder is
answer 3</p></li>
</ol>
<p>NO CLUE ON ANY OF THESE… PLEASE HELP ME BY EXPLAINING</p>
<ol>
<li> If you rotate a circle centered at the origin around an axis, you get a sphere. The radius of that circle is 2, so the volume of the sphere is 4/3(pi)(2)^2=(16/3)pi which is around 16.8.</li>
</ol>
<p>too lazy to answer the others...</p>
<ol>
<li>If volume = surface area for cylinder,
pi (r^2) h = 2 pi r^2 + 2 pi r h
which simplifies to rh = 2r + 2h = 2 (r+ h)
or r = 2(1 + r/h) = 2 + 2r/h which is > 2</li>
</ol>
<p>If r is an integer and > 2, the smallest value is 3; it occurs when
3 = 2 + 2(3/h) or when r=3 and h=6.</p>
<h1>2</h1>
<p>The radius of the base of the cone is 5. A radius from the center of the sphere to the edge of the cylinder connecticting to the base radius of the cone will have a length of 13</p>
<p>this means that the height of the cone is 12</p>
<p>volume of a cone is (1/3)pi(r^2)(h).... (1/3)(pi)(5^2)(12)</p>