General question about finding area of a solid by rotating axis

1. Feb 1, 2005

KataKoniK

I just have a general question here. There's this question in the textbook that asks to sketch a graph and then find the volume generated by revolving the region about the x-axis. The three equations they give is y = x, y = 0, x = 1.

Aren't we suppose to sketch a graph of those three equations? Because in the sols manual, they graph instead, y = x^3 and x + y = 10

2. Feb 1, 2005

hypermorphism

The solutions manual may be for a different edition, because there is no reason to graph the two equations it contains with respect to the original question.

3. Feb 1, 2005

KataKoniK

Thanks. I thought there was some mathematical reasoning behind graphing those two equations in the manual.

4. Feb 1, 2005

dextercioby

Nevermind the solution.In the original form,the text doesn't make any sense...The volumes considered are either 0 or infinite...

Daniel.

5. Feb 1, 2005

Thanks Dan

6. Feb 1, 2005

hypermorphism

Hi dexter,
I believe the text is talking about rotating the area contained by those 3 equations, which is a right-triangle with a vertex at the origin.

7. Feb 2, 2005

Galileo

Indeed, by rotating the region bounded by the three graphs you get a cone of height 1 and radius 1.