High School

The volume of a cone with a radius of 7 cm is [tex]$147 \pi$[/tex] cubic centimeters. Which expression can be used to find [tex]$h$[/tex], the height of the cone?



A. [tex]$147 \pi = \frac{1}{3}(7)(h)^2$[/tex]

B. [tex]$147 \pi = \frac{1}{3} \pi \left(7^2\right)(h)$[/tex]

C. [tex]$147 \pi = \frac{1}{3} \pi h$[/tex]

D. [tex]$147 \pi = \frac{1}{3} \pi(7)(h)$[/tex]

Answer :

The volume of a cone is given by the formula

$$
V = \frac{1}{3}\pi r^2 h.
$$

Given that the volume is $147\pi$ and the radius is $7$ cm, we substitute these values into the formula:

$$
147\pi = \frac{1}{3}\pi (7)^2 h.
$$

Notice that $(7)^2 = 49$, so the equation becomes

$$
147\pi = \frac{1}{3}\pi \cdot 49 \cdot h.
$$

This expression corresponds to the option

$$
147 \pi = \frac{1}{3} \pi\left(7^2\right)(h).
$$

Thus, the correct expression to find $h$ is

$$
147 \pi = \frac{1}{3}\pi\left(7^2\right)h.
$$

If we solve for $h$, we can multiply both sides by $3$ and then divide by $\pi \cdot 49$:

$$
h = \frac{147\pi \cdot 3}{\pi \cdot 49} = \frac{441}{49} = 9.
$$

Therefore, the expression that can be used to find the height $h$ of the cone is

$$
147\pi = \frac{1}{3}\pi\left(7^2\right)h.
$$