<p>Can someone put me in the right direction?</p>
<p>I am stuck on this hw problem.</p>
<p>Find an equation for the surface of revolution generated by revolving the curve in the indicated coordinate plane about the given axis.</p>
<p>Equation xy = 2 in the xy plane axis of rev: x</p>
<p>Hmm, wait
I might have gotten it with a little " unconventional " math</p>
<p>y^2 + z^2 = (2/x)^2</p>
<p>does that seem right?</p>
<p>hmm... :) I know how to do this but I'm still in Calc 2. :) It seems right. I can't remember what this actually looks like (the name for it). </p>
<p>Let me do a little homework and I'll get back to you m8.</p>
<p>are you finding surface area? I dont understand that question very well especially because there are no limits of integration...but here:</p>
<p>xy=2</p>
<p>y= 2/x
delta surface area = 2<em>pi</em>r<em>slant length
delta surface area = 2</em>pi<em>(2/x)</em>(square root(1 + (dy/dx)^2)<em>delta x
delta surface area = 2</em>pi<em>(2/x)</em>(square root(1+ (-2(x^-2)^2) * delta x</p>
<p>delta surface area = 2<em>pi</em>(2/x)* (square root of(1 +(-2(x^-4)) * delta x</p>
<p>Surface area = integral of [2<em>pi</em>(2/x)<em>(square root of(1+(-2(x^-4)))</em>dx]</p>
<p>no math symbols..this is bothersome...</p>
<p>yeah for calc III stuff and up its definitely better to learn LaTeX and take it over to the guys at AoPS. theyll get it for you.</p>
<p>LadyinRed, he's asking for the equation of the surface of revolution, not the surface area of it.</p>
<p>Man, I got an A in Calc III last semester, but I can't remember how to do this. I looked in my math book, but I think I'd need my notes to be able to do this. Haha, on the SAT yesterday I thought about using Lagrange multipliers for one of the problems, until I couldn't completely remember the formula.</p>
<p>yeah, I figured that wasn't the question...oh well, gave me practice with surface area anyway.
I have no idea what surface of revolution means...
I'm in Calc BC - I don't know if that corresponds to III in the number system.</p>
<p>surface revolution area is very easy. :)</p>
<p>Now restate your question please. I, like lady, am confused</p>
<p>btw, ladyinred, i'm also in calc bc but its considered calc 2. You should have covered surface revolutions for the AP exam</p>
<p>yes - easy it is. surface area of revolutions makes me happy...</p>
<p>it's considered calc 2 huh? well, that sucks. Then I suppose I can't help.</p>
<p>ConstantU4ea, the question is fine, you're just not understanding it; he's asking for the equation for the surface of revolution generated in the xyz plane by rotating xy=2 around the x-axis. Once you get in Calc III you'll understand it.</p>