The picture below illustrates a special type of conic section called a circle. Which of the following offers the best description of how a circle is formed? A. The plane passes through only one nappe of a right circular cone and is perpendicular to its base

B. The plane passes through both nappes are they right circular cone and is perpendicular to its base

C. The plane passes through only one nappe of a right circular cone and is parallel to its base

D. The plane passes through the vertex of a right circular cone

For every corresponding pair of cross sections, the area of the cross section of a sphere with radius r is equal to the area of the cross section of a cylinder with radius and height 2r minus the volume of two cones, each with a radius and height of r. a cross section of the sphere is and a cross section of the cylinder minus the cones, taken parallel to the base of cylinder, is the volume of the cylinder with radius r and height 2r is and the volume of each cone with radius r and height r is 1/3 pie r^3. so the volume of the cylinder minus the two cones is therefore, the volume of the cylinder is 4/3pie r^3 by cavalieri's principle. (fill in options are: r/2- r- 2r- an annulus- a circle -1/3pier^3- 2/3pier^3- 4/3pier^3- 5/3pier^3- 2pier^3- 4pier^3)