<p>Can someone help me please? Thanks in advance! :-)</p>
<p>Let R be the region enclosed by the graph y=sqrt(x-2), the vertical line x=11 and the x-axis.</p>
<p>Find the volume when R is rotated about the horizontal line y=4.</p>
<p>Well this problem is a washer problem...</p>
<p>First it helps to draw out the graph and figure out the intersection points. Just so you have an idea of the intersections, you could set y^2+2=11 and solve for y and you'll get + or - 3. +3 is the only useful solution here. Just to make sure I got y^2+2 by solving for x from the inital equation you gave.</p>
<p>Okay. Now using the formula for the Volume of a washer = pi x (R^2 - r^2) x h</p>
<p>So your representative washer should have it's center point on the line y=4. It's inner radius will go from y=4 to the greater function (sqrt(x-2)). So r is 4 - sqrt(x-2). The total radius will go from y=4 to the x axis to R = 4. And also the height or thickness of the washer will be delta x.</p>
<p>When you plug into the equation you'll get pi x ( (4-sqrt(x-2))^2 - (4)^2) x dx</p>
<p>When you sum up all these disks you'll get the total volume, I'm assuming you know about reimann sums and stuff.</p>
<p>So your equation for the volume of the solid should be V = pi x intergral from 2 to 11 of (4-sqrt(x-2))^2 - 16 dx. Don't have my graphing calculator with me so I can't get you the solution, but i hope this helps!</p>
<p>thanks!, but I already got it ^__^</p>