Check , Volumes for Calculus 1

[rocomath]

Check please, Volumes for Calculus 1

Been a while since I've done these type of problems, check please!

http://img70.imageshack.us/img70/3558/volumes1iy0.jpg"

http://img70.imageshack.us/img70/6768/volumes2aa9.jpg"

1. Find the volume of the solid generated by revolving the region about the y-axis:
xy=5, x=0, y=1, y=3

2. Find the volume of the solid generated by revolving the region about the x-axis:
y=-7x+14, y=7x, x=0

3. Find the volume of the solid generated by revolving the region about the y-axis:
y=x^3, x=2, y=1

4. Use the shell method to find the volume of the solid generated by revolving the region about the x-axis:
y=7x^2, y=7sqrt(x)

5. Find the volume of the solid generated by revolving the region about the y-axis:
y=1/2(x-2)^2, y=2

 

[rocomath]

Not sure about 2.

Mistake on 4, 189pi/10.

 

[rocomath]

5. 56pi/5

Can I get help on this one.

The base of a solid is a circular disc with radius 3. Find the volume of the solid if parallel cross-sections perpendicular to the base are isosceles triangles with the hypotenuse lying along the base.

 

[baileykd]

isosceles triangles can have 3 equal sides. This is the angle I am trying to work, however, I keep getting 0 myself.
What do you have so far?

 

[baileykd]

y=(9-x^2)^1/2

Area = (bh)/2
= (9-x^2)/2
??

 

[rocomath]

isosceles triangles can have 3 equal sides. This is the angle I am trying to work, however, I keep getting 0 myself.
What do you have so far?

You're thinking equilateral triangles.

I already corrected & solved all the problems though, thanks!