If a plane intersects all edges of a pyramid, parallel to its bases, it divides the solid into two others: a new pyramid and a pyramid trunk. Given the following regular pyramid trunk, we have:
the bases are parallel and similar regular polygons;
the lateral faces are congruent isosceles trapezoids.
We have the following areas:
a) lateral area (THEL): sum of the areas of the congruent isosceles trapezius forming the lateral faces.
b) total area (THET): sum of the lateral area with the sum of the smaller base areas (THEB) it's bigger (THEB).
|THET = AL+ AB+ AB|
The volume of a regular pyramid trunk is given by:
Since V is the volume of the pyramid and V 'is the volume of the pyramid obtained by the section, the relation is valid: