Illustration of a conical bifrustum created by three parallel planes of circles with the middle plane…

Illustration of a decagonal bifrustum created by three parallel planes of decagons with the middle plane…

Illustration of a hexagonal bifrustum created by three parallel planes of hexagons with the middle plane…

Illustration of a octagonal bifrustum created by three parallel planes of octagons with the middle plane…

Illustration of a square bifrustum created by three parallel planes of squares with the middle plane…

An illustration of a composite figure made up of a quadrilateral frustum and half of a cylinder. Frustum…

Illustration of a right circular cone that has been cut by a plane parallel to the base. The lower part…

Illustration of a right circular cone that has been cut by a plane parallel to the base. The top section…

An illustration of a circular cone with the top cut off by a plane parallel to the base. The remaining…

Illustration of a frustum of a right circular cone with hidden edges shown. When a cone is cut by a…

Illustration of a frustum of a right circular cone. When a cone is cut by a plane parallel to the base,…

"The lateral area of a frustum of a cone of revolution is equal to half the sum of the circumferences…

"The volume of a frustum of a circular cone is equivalent to the sum of the volumes of three cones whose…

Illustration of a pyramid and with a regular polygon inscribed in and circumscribed about a cone. "If…

An illustration of a cube divided into 6 equal pyramids to illustrate how volume can be found.

Illustration of a decagonal pyramid that has been cut by a plane parallel to the base. The top section…

Illustration of a hollow decagonal pyramid that has been cut by a plane parallel to the base. The top…

Illustration of a decagonal pyramid that has been cut by a plane parallel to the base. The top section…

Illustration of a hollow septagonal/heptagonal pyramid that has been cut by a plane parallel to the…

If a pyramid be cut by a plan parallel to the base, so as to form two parts, the lower part is called…

"The part of any solid between two planes, which may be either parallel or inclined to each other: as,…

Diagram used to prove the theorem: "The volume of the frustum of a pyramid (cone) is equal to the sum…

The frustum of a pyramid is the portion of a pyramid included between the base and a section parallel…

The frustum of a triangular pyramid is equivalent to the sum of three pyramids whose common altitude…

Illustration of a right hexagonal pyramid that has been cut by a plane parallel to the base. The lower…

Illustration of a frustum of a hexagonal pyramid (including cross-section).

Illustration of a right hexagonal pyramid that has been cut by a plane parallel to the base. The top…

Illustration of a right hexagonal pyramid that has been cut by a plane parallel to the base. The top…

Illustration of a right hexagonal pyramid that has been cut by a plane parallel to the base. The top…

Illustration of a skewed hexagonal pyramid that has been cut by a plane parallel to the base. The top…

Illustration of a hollow nonagonal pyramid that has been cut by a plane parallel to the base. The top…

Illustration of a right octagonal pyramid, with hidden edges shown, that has been cut by a plane parallel…

Illustration of a right octagonal pyramid that has been cut by a plane parallel to the base. The lower…

Illustration of a hollow octagonal pyramid that has been cut by a plane parallel to the base. The top…

Illustration of a frustum of a pentagonal pyramid (including cross-section).

Illustration of a right pentagonal pyramid that has been cut by a plane parallel to the base. The top…

Illustration of a hollow pentagonal pyramid that has been cut by a plane parallel to the base. The top…

Illustration of a right pentagonal pyramid, with a height much larger than the edge lengths of the base,…

Illustration of a right pentagonal pyramid, with a height smaller than the edge lengths of the base,…

Illustration of a hollow pentagonal pyramid that has been cut by a plane parallel to the base. The top…

Illustration of a skewed pentagonal pyramid that has been cut by a plane parallel to the base. The top…

The frustum of a pyramid is the portion of a pyramid included between the base and a section parallel…

The volume of the frustum of any pyramid is equal to the sum of the volumes of three pyramids whose…

An illustration of a pyramid with the top cut off by a plane parallel to the base. The remaining part…

An illustration of a pyramid with the top cut off by a plane parallel to the base. The remaining part…

The frustum of a pentagonal pyramid is the portion of a pyramid included between the base and a section…

An illustration of a pyramid with the top cut off by a plane parallel to the base. The remaining part…

Illustration of pentagonal and triangular pyramids cut by a plane parallel to the bases.

Illustration of a right rectangular pyramid that has been cut by a plane parallel to the base. The lower…

Illustration of a right rectangular pyramid that has been cut by a plane parallel to the base. The top…

Illustration of a right rectangular pyramid that has been cut by a plane parallel to the base. The top…

Illustration of a right rectangular pyramid that has been cut by a plane parallel to the base. The lower…

Illustration of a right rectangular pyramid that has been cut by a plane parallel to the base. The top…