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

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

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

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

Answer :

The formula for the volume of a cone is

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

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

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

Since $7^2 = 49$, the equation becomes:

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

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

To solve for $h$, we can multiply both sides of the equation by 3:

$$
441\pi = \pi(49)h.
$$

Next, we cancel $\pi$ from both sides:

$$
441 = 49h.
$$

Finally, dividing both sides by 49 gives:

$$
h = \frac{441}{49} = 9.
$$

Thus, the height of the cone is 9 cm, and the correct expression is:

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