Answer:
![\boxed {\boxed {\sf v=2142 \ in^3}}](https://img.qammunity.org/2021/formulas/mathematics/high-school/qi9hfunx0c4au3n1yo39dep8ma3o0k1mkz.png)
Explanation:
The volume of a triangular prism can be found by multiplying the area of the base by the height.
![v=B*h](https://img.qammunity.org/2021/formulas/mathematics/high-school/7tw0t0l3m4caguufe1ibm7smsexosl5o2s.png)
The area of a triangle can be found by multiplying the base, height, and 1/2. In this problem, the base and height are width and length.
![B= (1)/(2) *w*l](https://img.qammunity.org/2021/formulas/mathematics/high-school/2nfvzrs73xlg1g55bmatk9w7c84ezf6md7.png)
Substitute this formula in for B.
![v= ((1)/(2) *w*l)*h](https://img.qammunity.org/2021/formulas/mathematics/high-school/unz4ebfq8gtp60zzfw4oh4c6acxrj48jsp.png)
We know that the width is 17 inches, the length is 12 inches, and the height is 21 inches. Substitute the values in.
![w= 17 \ in \\l= 12 \ in \\h= 21 \ in](https://img.qammunity.org/2021/formulas/mathematics/high-school/rz0f6g90vs3tkj5h6pmb5fcisvqlru5k9i.png)
![v= ((1)/(2)* 17 \ in * 12 \ in ) * 21 \ in](https://img.qammunity.org/2021/formulas/mathematics/high-school/7gepb6u2snzvoz68c3ay4slop39n23sx1f.png)
Solve inside the parentheses first. Multiply 17 and 12.
![v=((1)/(2)*204 \ in^2) * 21 \ in](https://img.qammunity.org/2021/formulas/mathematics/high-school/iwa22n65crotj61hvz2ny2amslg400cywf.png)
Finish solving the parentheses by multiplying by 1/2 or dividing by 2.
![v=102 \ in ^2 * 21 \ in](https://img.qammunity.org/2021/formulas/mathematics/high-school/shyk51soqqnnv9sshrrqtnac8nxu10gzh6.png)
Multiply.
![v=2142 \ in^3](https://img.qammunity.org/2021/formulas/mathematics/high-school/38y470tb0jrfbbrqejlqrqjwgl1nrr65a6.png)
The volume of the triangular prism is 2,142 cubic inches.