A cone is cut out of the center of a pyramid with a rectangular base. The rectangular base has side lengths of 15 and 10 units. The cone has a diameter of 9 and a height of 12. The pyramid and cone have the same height. What is the volume of the shaded portion of the composite figure? Express your answer in terms of π.

check the picture below.

well, the angle at the vertex d is clearly not a right-angle, let's check for the one at the vertex f which does look like,   however if it's indeed, that means ef is perpendicular to df, in which case their slopes will be negative reciprocal of each other.

so the negative reciprocal of the slope of ef is 1, however the slope of df is not 1, is 1/2, so nope, they're not perpendicular lines.

it is a. 4.2 because 7.6-3.4 gets the remaining length of 4.2. i might be wrong but i am pretty sure this is the answer.

8.3 and the 3 is repeating

hope this .