Answer
yz-plane that connect the top of the square to the circle.
Work Step by Step
There are many different solids that fit the given description. However, any possible solid must have a circular horizontal
cross-section at its top or at its base. Here we illustrate a solid with a circular base in the xy-plane. (A circular cross-section at the top results in an inverted version of the solid described below.) The vertical cross-section through the center of the base that is parallel to the xz-plane must be a square, and the vertical cross-section parallel to the yz-plane (perpendicular to the square) through the center of the base must be a triangle with two vertices on the circle and the third vertex at the center of the top side of the square.
The solid can include any additional points that do not extend beyond these
three "silhouettes" when viewed from directions parallel to the coordinate
axes. One possibility shown here is to draw the circular base and the vertical
square first. Then draw a surface formed by line segments parallel to the
yz-plane that connect the top of the square to the circle.
