Wednesday

October 1, 2014

October 1, 2014

Posted by **Mick** on Monday, February 14, 2011 at 7:07pm.

- geometry -
**Reiny**, Monday, February 14, 2011 at 7:34pmany solid that comes to a vertex or point has the formula

V = (1/3) (base area) x (height)

I you know Calculus you could take the region bounded by the x-axis, the y-axis and a line with x-intercept of h and y-intercept of r and rotate it about the x-axis

The result will be a cone with radius r and height h

the equation of that line is

y = (-r/h)x + r

the generated volume

= π[integral]y^2 dx

= π[integral] (r^2x^2/h^2 - 2r^2x/h + r^2) dx

= π [r^2x^3/(3h^2) - r^2x^2/h + r^2x] from 0 to h

= π(r^2h/3 - r^2h + r^2h - 0)

= π(r^2)(h)/3

= (1/3)(πr^2)(h) or (1/3)basearea x height

When I was still teaching, I had a cylinder and a cone, both with the same radius and height.

In class we would fill the cone with water and pour it into the cylinder, and do that until the cylinder was full.

We were able to fill and pour THREE times, showing that the volume of the cone was

(1/3) of the volume of the cylinder.

notice

volume of cylinder = πr^2h

volume of cone = (1/3)πr^2h

**Answer this Question**

**Related Questions**

geometry - A hemispherical dome holds a volume of 486π..find the surface ...

geometry - Looking at formulas, which 2 shapes describe this relationship: the ...

Math - When something says that I'll be tested on formulas for perimeter and ...

Statistics - Hi, My professor gave us the formulas for sample variance and ...

math - Okay. So i'm doing this project for my geometry class about different ...

Math - Use the formulas V=s❸ andA=6s❷ to calculate the volume and ...

math - Can you describe some common formulas that you use in your life? Like ...

4th grade - I like to know few Formulas in Algebra, What formulas we have use in...

geometry - The coordinates for a rhombus are given as (2a, 0), (0, 2b), (–2a, 0...

physics thermodynamics - A gas expands from a volume of 2.00m^3 to 6.00m^3 and ...