solid angle

n. An angle having a value equal to the area on a sphere subtended by a surface, divided by the square of the radius of that sphere. Solid angles are measured in steradians.

solid angle

n (Mathematics) a geometric surface consisting of lines originating from a common point (the vertex) and passing through a closed curve or polygon: measured in steradians

sol′id an′gle

n. an angle formed by three or more planes intersecting in a common point or formed at the vertex of a cone.

Thesaurus

Noun

solid angle - an angle formed by three or more planes intersecting at a common point (the vertex)angle - the space between two lines or planes that intersect; the inclination of one line to another; measured in degrees or radians

Solid Angle

solid angle

[′säl·əd ′aŋ·gəl] (mathematics) A surface formed by all rays joining a point to a closed curve.

Solid Angle

a surface formed by rays having a common origin and passing through a closed curve (Figure 1). Sometimes, particularly in Soviet usage, the term “solid angle” is applied to the portion of space bounded by such a surface. Trihedral and polyhedral angles are special cases of solid angles.

Figure 1

A measure of the solid angle subtended at a given point by a surface S is provided by the ratio AIR². Here, A is the area of the portion of a sphere, with center at the given point, that is cut by a conical surface with vertex at the point and with the perimeter of S as a directrix, and R is the radius of the sphere. Clearly, the measure of a solid angle is an abstract number. For example, the measure of a solid angle that encloses an octant, that is, oneeighth of space, is the number 4π R^2/8 R² = π/2 (Figure 2).

Figure 2

The unit of measure of a solid angle is called the steradian. It is equal to the solid angle subtended at the center of a sphere of unit radius by a portion of the sphere’s surface that is of unit area. The total solid angle about a point is equal to 4π steradians.

solid angle

solid angle

solid angle

sol′id an′gle

Solid Angle

solid angle

Solid Angle

solid angle

Words related to solid angle

noun an angle formed by three or more planes intersecting at a common point (the vertex)

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