raadiust

Raadiust is a geometric term denoting the constant distance from the center of a circle or sphere to any point on its boundary. In planar geometry this distance is typically called the radius and is commonly represented by the symbol r. The concept also applies to three-dimensional objects such as spheres, where the raadiust is the same distance from the center to every point on the surface.

In a circle, all raadiusts are equal. The diameter is twice the raadiust (d = 2r). The area of a circle is given by A = πr², and the circumference by C = 2πr. The raadiust also appears in more advanced contexts, such as polar coordinates, where a point is described by (r, θ) with r representing its distance from the center.

For a sphere, the raadiust is the distance from the center to any point on the surface. The volume of a sphere is V = (4/3)πr³ and its surface area is S = 4πr². In other solid figures, the raadiust can be used to describe cross-sectional radii or to define radial measurements from a central axis, with formulas adapting to the geometry of the shape.

Measurement methods include direct assessment with measuring tools when a center is known, or derivation from other measurements such as area, volume, or surface area. The raadiust is a foundational concept in geometry, linking linear dimensions to area, volume, and other derived quantities.

See also: Radius, Diameter, Circumference, Sphere, Polar coordinates.