Answer: 800π km³
Explanation: To find the volume of a cylinder, start with the formula for the volume of a cylinder.
![Volume = \pi r^(2) h](https://img.qammunity.org/2020/formulas/mathematics/middle-school/2yi00f6yvzmqlbbg0xttqts4xie4hbwn79.png)
In this example, notice that our cylinder has a radius diameter of 20 km. Since we are given the diameter of the cylinder, we will need to divide 20 by 2 in order to find the radius. 20 ÷ 2 = 10, this means that our radius of the cylinder is 10 km and the height of the cylinder is 8 km. Now, we can plug these numbers into our formula.
![Volume = (\pi) (10 km)^(2) (8km)](https://img.qammunity.org/2020/formulas/mathematics/middle-school/53va88cxvcxpqubkza1hrsk1obb9oc52ao.png)
Now, let's simplify the exponent. Remember that squaring a number just means multiplying the number by itself. In this case, 10 km² is equal to 10 km multiplied by 10 km or 100 km².
![Volume = (\pi) (100 km^(2)) (8 km)](https://img.qammunity.org/2020/formulas/mathematics/middle-school/wt07h2wwp3c84adr8ll5spnn3lsf1afvgt.png)
![Volume = 800\pi km^(3)](https://img.qammunity.org/2020/formulas/mathematics/middle-school/b2x2x4bg4i6dcmb8joid87oe7zf7d8s5ec.png)