Definition

1. Noun:
   • The angle formed by two edges of a polyhedral angle: In geometry, a "face angle" is the angle between two adjacent edges that meet at a vertex on a single face of a polyhedron. It is an interior angle of a polygonal face.

Usage

• The term "face angle" is used specifically in the context of solid geometry and polyhedra (three-dimensional shapes with flat faces). It describes an angle on the surface of the shape, not the angle between faces (which is a dihedral angle).

Examples

• Noun:
  • To calculate the surface area, you first need to measure each face angle of the pyramid.
  • In a regular tetrahedron, all face angles are equal.
  • The carpenter checked the face angle of the wooden block to ensure a precise fit.

Advanced Usage

• "Internal face angle": This phrase is sometimes used for clarity to specify it is the interior angle of the polygon forming the face, as opposed to an external angle.
  • The sum of the internal face angles in a pentagonal face is 540 degrees.

Variants and Related Words

• Dihedral angle (n): The angle between two intersecting planes or faces of a polyhedron. This is distinct from a face angle.
  • The dihedral angle between the side and base of the prism is 90 degrees.
• Polyhedral angle (n): The figure formed by three or more planes meeting at a common point (the vertex). A face angle is a component of a polyhedral angle.
  • The polyhedral angle at the apex of the pyramid consists of several face angles.

Synonyms

• Interior angle of a face: A more descriptive synonym.
• Plane angle at a vertex: A technical synonym emphasizing it lies on a flat surface.

Notes

• "Face angle" is a compound noun. The core term being explained is this specific geometric concept. It should not be confused with the separate words "face" or "angle" used independently.

Noun

1. the angle formed by two edges of a polyhedral angle