At first, let us define an angle in radians:
Consider an arc of lenght L over an angle alfa in a circle with radius R. The angle alfa is defined as alfa=L/R [in radians]. Similarly, an stereo angle is defined in a sphere with radius R over an area S, and the stereo angle alfa is defined as: alfa=S/R^2 [in steradians]. The sphere has S=4.pi.R^2, so the corresponding angle of the sphere in steradians is
alfa=S/R^2
alfa=4.pi.R^2/R^2
alfa=4.pi [steradians]
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A sphere has no faces an corners. The term "faces" and "corners" are applied to polyhedrons, figures with flat surfaces.
A sphere has no edges, because an edge is defined as where two faces meet. Likewise, it has no faces, because a face is defined as the flat surface of an object. Likewise, it has no corners either.
The surface area is 1,385.4 cm2
A sphere. In Geometry, it is a round solid figure. Every point on it's surface is an equal distant from it's center.