The volume of a cone with a height of 6 cm is [tex]8 \pi[/tex] cubic centimeters. Which expression can be used to find [tex]r[/tex], the radius of the base of the cone?

A. [tex]6=\frac{1}{3} \pi\left(r^2\right)(8 \pi)[/tex]

B. [tex]8 \pi=\frac{1}{3} \pi(r)\left(6^2\right)[/tex]

C. [tex]8=\frac{1}{3} \pi(r)(8 \pi)[/tex]

D. [tex]8 \pi=\frac{1}{3} \pi\left(r^2\right)(6)[/tex]



Answer :

Let's find the expression to determine [tex]\( r \)[/tex], the radius of the base of the cone, given certain values. The volume [tex]\( V \)[/tex] of a cone can be calculated using the formula:

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

Where:
- [tex]\( V \)[/tex] is the volume,
- [tex]\( r \)[/tex] is the radius of the base,
- [tex]\( h \)[/tex] is the height,
- [tex]\( \pi \)[/tex] is a constant (approximately 3.14159).

We are provided with:
- The volume of the cone, [tex]\( V = 8 \pi \)[/tex] cubic centimeters,
- The height of the cone, [tex]\( h = 6 \)[/tex] cm.

The objective is to identify the correct expression for [tex]\( r \)[/tex].

To start, substitute the given values into the volume formula:

[tex]\[ 8 \pi = \frac{1}{3} \pi r^2 \times 6 \][/tex]

Now, let's simplify the expression step-by-step:

1. Arrange the equation:

[tex]\[ 8 \pi = \frac{1}{3} \pi \cdot r^2 \cdot 6 \][/tex]

2. Combine the π terms:

[tex]\[ 8 \pi = \frac{1}{3} \pi \cdot 6 \cdot r^2 \][/tex]

3. Simplify the constants:

[tex]\[ 8 \pi = 2 \pi r^2 \][/tex]

Therefore, the correct expression for finding [tex]\( r \)[/tex] is:

[tex]\[ 8 \pi = \frac{1}{3} \pi \left( r^2 \right)(6) \][/tex]

This matches precisely with one of the given answer choices:

[tex]\[ 8 \pi=\frac{1}{3} \pi\left(r^2\right)(6) \][/tex]

This is the correct answer.