chokkaku

Chokkaku is a Japanese term written with the characters 直角 and pronounced chokkaku. It denotes a right angle, that is, an angle of exactly 90 degrees. The word is used in mathematics and geometry to specify the relationship between two perpendicular lines or surfaces.

In mathematical usage, chokkaku appears in phrases such as chokkaku sankakukei (直角三角形), meaning a right triangle, and in statements about perpendicularity, where lines that form a right angle are said to be chokkō (直交) with respect to each other. The standard symbol for a right angle in diagrams is a small square placed at the vertex, and the angle can be measured in degrees as 90°.

Chokkaku also appears in practical contexts beyond pure math. In carpentry, architecture, and design, achieving chokkaku is essential for constructing perpendicular joints and ensuring accurate layouts. Tools like try squares and set squares are commonly used to verify right angles. In computer graphics and physics, right angles are frequently described when dealing with perpendicular vectors or axes, reflecting the same geometric concept captured by chokkaku.

Etymology and related terms: the word is formed from 直 meaning “straight” or “direct” and 角 meaning “angle.” Related terms include chokkō (直交), meaning perpendicular, and phrases for angle measurements and geometric relationships.