The volume of a cone is 261.8 cm cubed and the height of the cone is 10 cm. What is the approximate radius of the cone?

10 cm

15 cm

20 cm

5 cm

1 answer

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

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

where:

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

Given:

  • \( V = 261.8 , \text{cm}^3 \)
  • \( h = 10 , \text{cm} \)

We can rearrange the formula to solve for \( r^2 \):

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

Now, substituting the given values:

\[ r^2 = \frac{3 \times 261.8}{\pi \times 10} \]

Calculating this step by step:

  1. \( 3 \times 261.8 = 785.4 \)
  2. \( \pi \times 10 \approx 31.4 \) (using \( \pi \approx 3.14 \))
  3. Now calculate:

\[ r^2 \approx \frac{785.4}{31.4} \approx 25.0 \]

Now, taking the square root to find \( r \):

\[ r \approx \sqrt{25.0} \approx 5.0 , \text{cm} \]

Thus, the approximate radius of the cone is \( \text{5 cm} \).

The answer is 5 cm.