### Home > CCG > Chapter 9 > Lesson 9.2.4 > Problem9-103

9-103.

Find the volumes of the solids below. Homework Help ✎

1. cylinder with a hole

Recall the formula for the volume of a cylinder.
Cylindrical volume = (area of the base)×(height)

1. regular octagonal prism

Divide the octagonal base into congruent triangles to find its area.

Now use the formula (volume) = (area of the base)×(height) to find the volume of the prism.

Base Area $≈ 19.3\text{ units}²$
Volume $≈ (19.3)(7) ≈ 135.2\text{ units}³$