The volume of the shaded portion in the composite figure, excluding the cone inside a triangular pyramid, is
units³. Thus, the correct answer is (D)
units³.
To find the volume of the shaded portion, we need to calculate the volume of the triangular pyramid and subtract the volume of the cone.
1. Volume of Triangular Pyramid:
The base of the triangular pyramid is a rectangle with dimensions
and 10, so the base area is
. The height of the pyramid is
.
2. Volume of Cone:
The diameter of the cone is 9, so the radius r is
. The height \( h \) is 12.
Now, subtract the volume of the cone from the volume of the pyramid to get the volume of the shaded portion:
Now, simplify this expression to get the final answer.
Therefore, the correct answer is option (D)
units³.