90degree

90degree, written as 90°, is an angular measurement equal to one quarter of a full rotation. In radians, 90 degrees equals pi/2. This value is widely recognized as the standard measure of a right angle.

The term 90degree is most closely associated with the concept of a right angle, the angle formed by two perpendicular lines. Perpendicular lines intersect to create a 90° angle, and any two such lines are said to be orthogonal. In a right triangle, one angle is 90°, and the other two angles are complementary, meaning they sum to 90°.

In practical terms, 90degree is a fundamental reference in geometry, engineering, architecture, and computer graphics. It defines axis orientation in Cartesian coordinate systems, determines the orientation of objects during rotations (a quarter-turn), and guides construction and design where vertical and horizontal alignments are required. In navigation, a bearing of 90° typically corresponds to east on standard compass conventions.

The degree is a historical unit of angular measure defined as 1/360 of a circle, with the symbol °. Today it remains the standard unit for everyday angular measurements in science, education, and industry, while radians are often used in higher mathematics and physics for calculations involving rotational motion.

See also: angle, perpendicular, right angle, rotation, compass bearing, radians.

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