90kraadi

90kraadi is the Estonian term for ninety degrees, commonly used to denote a right angle in geometry and everyday language. In mathematics, a 90-degree angle is formed by two perpendicular lines and represents one quarter of a full circle. It corresponds to pi over two radians (π/2) and is a fundamental reference angle in various geometric and trigonometric contexts.

In geometry and design, right angles define the corners of many shapes, such as squares and rectangles, and they underpin many constructions, proofs, and coordinate calculations. In practical applications, 90 degrees is important for ensuring perpendicularity in construction, architecture, and engineering, as well as in computer graphics, where right angles influence object alignment and rendering.

The concept also appears in measurements and navigation, where maintaining right angles helps with precise survey work, mapping, and layout planning. In education, students learn to identify 90-degree angles using symbols, instruments, and diagrams, often relating them to complementary angles that sum to 90 degrees.

90kraadi is primarily a linguistic expression for the concept of a right angle in Estonian, but the idea is universal in geometry. While the phrase can appear in educational texts, signage, or casual speech to describe corners and perpendicularity, it does not denote a single, distinct entity beyond its mathematical meaning. See also: right angle, perpendicularity, geometry.