unghi

Unghi is the geometric concept of an angle, as used in Romanian. An angle is formed by two rays that share a common endpoint, called the vertex. The two rays are the sides of the angle, and the measure of the angle is the size of the rotation needed to align one side with the other. Angles are typically expressed in degrees or radians.

Angles are classified by their size: acute angles are less than 90 degrees, right angles are exactly 90 degrees, obtuse angles are between 90 and 180 degrees, straight angles are exactly 180 degrees, and reflex angles are greater than 180 degrees (up to 360 degrees). The standard unit system relates degrees and radians: a full rotation is 360 degrees or 2π radians, and 180 degrees equals π radians. Consequently, 1 degree equals π/180 radians.

In geometry, angles have several important properties and relations. The sum of interior angles in a triangle is 180 degrees, and the sum of angles around a point is 360 degrees. Angles can be measured with a protractor or computed via trigonometric functions when the sides are known. Other key concepts include angle addition, complementary angles (sum to 90 degrees), supplementary angles (sum to 180 degrees), vertical angles (opposite angles formed by intersecting lines that are congruent), and angle bisectors, which divide an angle into two equal angles.

Applications of angles span many fields, including architecture, physics, computer graphics, surveying, and navigation. Etymology: the Romanian term unghi derives from Latin angulus, meaning corner or angle.