June 26, 2019
A pyramid is a polyhedron, whose base can be any polygon and whose lateral faces are triangles with a common vertex (apex of the pyramid).
The height of the pyramid is the measure of the perpendicular line segment from the apex to the base.
The apothem of a regular pyramid is the height of one of its lateral faces.
Unfold of a Pyramid
Types of Pyramids
The base of a regular pyramid is a regular polygon and its faces are equally sized.
The base of an irregular pyramid is an irregular polygon, and as a result, its faces are not equally sized.
A convex pyramid has a convex polygon as its base.
A concave pyramid has a concave polygon as its base.
A right pyramid has isosceles triangles as its lateral faces and its apex lies directly above the midpoint of the base.
An oblique pyramid does not have all isosceles triangles as its sides.
Types of the Pyramids by their Base
The base is a triangle.
The base is a square.
The base is a pentagon.
The base is a hexagon.
Calculation of the Apothem of a Pyramid
The apothem of a pyramid can be calculated if the height of the pyramid and apothem of the base are known. Apply the Pythagorean theorem and calcuate the hypotenuse for the shaded right triangle:
Calculation of the Lateral Edge of a Pyramid
The lateral edge of the pyramid can be calucated if the height of the pyramid and the radius of the base (or radius of the circumscribed circle) are known. Apply the Pythagorean theorem and calcuate the hypotenuse of the shaded right triangle.
Lateral Area of a Pyramid
Surface Area of a Pyramid
Volume of a Pyramid
Calculate the lateral area, surface area and volume of a square pyramid whose base edge is 10 cm and its height is 12 cm.
Calculate the lateral area, surface area and volume of a hexagonal pyramid whose base edge is 16 cm and its lateral edge is 28 cm.