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{{ printedBook.courseTrack.name }} {{ printedBook.name }} A pyramid is a polyhedron in which one face (the **base**) can be any polygon, and the other faces (the **lateral faces**) are triangles that meet at a common vertex called the **vertex** of the pyramid. Similar to the altitude of a triangle, the **altitude of a pyramid** is the segment from the vertex that is perpendicular to the plane of the base.

The length of the altitude is called the **height** of the pyramid. A pyramid is **regular** if its base is a regular polygon and its lateral faces are congruent, isosceles triangles. In a regular pyramid, the length of the altitude of each lateral face is sometimes referred to as the slant height of a pyramid .

If a pyramid is not regular, it is called **irregular** or **oblique**.