Find the volume of a cone with slant height of

29
29 feet and a radius of
20
20 feet. Use 3.14 for π. (The cone is not drawn to scale.) Click Here for Help Video 2

Click Here for Help Video


29
29 feet


20
20 feet

The height of the cone is
feet.

The volume of the cone is
cubic feet.

1 answer

To find the volume of a cone, we can use the formula:

\[ V = \frac{1}{3} \pi r^2 h \]

where \( V \) is the volume, \( r \) is the radius, and \( h \) is the height.

Step 1: Find the height of the cone.

We are given the slant height (\( l \)) and the radius (\( r \)). We can use the Pythagorean theorem to find the height (\( h \)) of the cone. The relationship between the radius, height, and slant height can be defined as:

\[ l^2 = r^2 + h^2 \]

Given:

  • Slant height \( l = 29 \) feet
  • Radius \( r = 20 \) feet

We can rearrange the equation to solve for \( h \):

\[ h^2 = l^2 - r^2 \]

Now, plug in the values:

\[ h^2 = 29^2 - 20^2 \]

Calculating \( 29^2 \) and \( 20^2 \):

\[ 29^2 = 841 \] \[ 20^2 = 400 \]

So,

\[ h^2 = 841 - 400 = 441 \]

Now, take the square root to find \( h \):

\[ h = \sqrt{441} = 21 \text{ feet} \]

Step 2: Calculate the volume of the cone.

Now that we have the height, we can substitute the radius and height into the volume formula:

\[ V = \frac{1}{3} \pi r^2 h \] \[ V = \frac{1}{3} \times 3.14 \times 20^2 \times 21 \]

Calculating \( 20^2 \):

\[ 20^2 = 400 \]

Now substitute this back into the volume formula:

\[ V = \frac{1}{3} \times 3.14 \times 400 \times 21 \] \[ V = \frac{1}{3} \times 3.14 \times 8400 \]

Calculate \( 3.14 \times 8400 \):

\[ 3.14 \times 8400 = 26376 \]

Now divide by 3:

\[ V = \frac{26376}{3} = 8792 \]

Final Answer

The volume of the cone is approximately 8792 cubic feet.