Kulmakulma

Kulmakulma is a Finnish term that refers to the angle at a corner. The word is used in mathematical and practical contexts to describe the angle formed by two intersecting lines or surfaces at a vertex. It is a compound built from kulma, meaning angle or corner, and is commonly encountered in school geometry as well as in construction-related discussions about joints and fittings.

In geometry, kulmakulma denotes the interior angle at a polygon’s vertex. The measure is given in degrees or radians. For a polygon with n sides, the sum of all interior kulmakulmat is (n−2)×180 degrees, and in a regular n-gon each interior kulmakulma equals [(n−2)×180]/n degrees. The concept is fundamental to understanding polygon properties, angle sums, and tessellations.

In practical settings such as carpentry and architecture, kulmakulma describes the angular relationship at a corner, for example the angle between a wall and a baseboard or between joined moldings. Accurate kulmakulma is important for fitting joints, cutting materials correctly, and ensuring straight, aesthetically pleasing corners. Common tools for setting or measuring kulmakulma include protractors, bevel gauges, and miter saws, depending on the context and precision required.

The term is primarily used in Finnish-language texts. In international mathematical contexts, the more common terms are interior angle or vertex angle. Etymologically, kulmakulma reflects its focus on the corner-based angle formed at a vertex. See also interior angle, polygon, and exterior angle.