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Hi everyone, I'm pretty new to Physics Forums but it seems like a fairly friendly community. :)
Determine the equation of the surface formed when the line x=3y is rotated about the x-axis.
x=3y is the given line.
First I write it in terms of x because it's simpler: [tex]y = \frac{1}{3} x[/tex]
The slope is 1/3, thus, and you have a diagonal line that passes through the origin in a 2-D graph with the X-Y plane.
Now, if you rotate this about the X-axis, you see you get a sort of cone. rather, two cones, one for each side of the y-axis ; these two cones have their tops(tips) facing each other.
How, though, can I determine an equation for the cone? I know there is a generic equation that involves x,y,z variables and a,b,c constants (I think it's something like.. [tex](x-a)^{2} + (y-b)^{2} = (z-c)^{2}[/tex] )
but what do I plug in for the variables and constants? I think I need to substitute [tex]\frac{x}{3}[/tex] for [tex] x [/tex] , or maybe with one of the other variables (y or z) but I'm not sure where and how.
If anyone could help me on this I would very much appreciate it. Thank you! :)
Homework Statement
Determine the equation of the surface formed when the line x=3y is rotated about the x-axis.
Homework Equations
x=3y is the given line.
The Attempt at a Solution
First I write it in terms of x because it's simpler: [tex]y = \frac{1}{3} x[/tex]
The slope is 1/3, thus, and you have a diagonal line that passes through the origin in a 2-D graph with the X-Y plane.
Now, if you rotate this about the X-axis, you see you get a sort of cone. rather, two cones, one for each side of the y-axis ; these two cones have their tops(tips) facing each other.
How, though, can I determine an equation for the cone? I know there is a generic equation that involves x,y,z variables and a,b,c constants (I think it's something like.. [tex](x-a)^{2} + (y-b)^{2} = (z-c)^{2}[/tex] )
but what do I plug in for the variables and constants? I think I need to substitute [tex]\frac{x}{3}[/tex] for [tex] x [/tex] , or maybe with one of the other variables (y or z) but I'm not sure where and how.
If anyone could help me on this I would very much appreciate it. Thank you! :)