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UpSolidAngleMeasure, SystemeInternationalUnit  Steradian subject fact
 Steradian documentation SI SolidAngleMeasure. Symbol: sr. It is the solid angle of a sphere subtended by a portion of the surface whose area is equal to the square of the sphere's radius. Another definition is: the solid angle which, having its vertex in the center of the sphere, cuts off an area of the surface of the sphere equal to that of a square with sides of length equal to the radius of the sphere. Steradian = m^2/m^2 = 1 is an instance of SolidAngleMeasure is an instance of SystemeInternationalUnit ConstantQuantity has axiom `(=> (instance ?FUNCTION UnaryConstantFunctionQuantity) (and (domain ?FUNCTION 1 ConstantQuantity) (range ?FUNCTION ConstantQuantity)))` is first domain of MagnitudeFn is second domain of measure UnitOfMeasure has axiom `(=> (and (equal (MeasureFn ?NUMBER ?UNIT) ?QUANT) (subclass ?UNIT ?QUANTTYPE) (not (equal ?QUANTTYPE UnitOfMeasure))) (subclass ?QUANT ?QUANTTYPE))` has axiom `(=> (and (instance ?FUNCTION RelationExtendedToQuantities) (instance ?FUNCTION BinaryFunction) (instance ?NUMBER1 RealNumber) (instance ?NUMBER2 RealNumber) (equal (AssignmentFn ?FUNCTION ?NUMBER1 ?NUMBER2) ?VALUE)) (forall (?UNIT) (=> (instance ?UNIT UnitOfMeasure) (equal (AssignmentFn ?FUNCTION (MeasureFn ?NUMBER1 ?UNIT) (MeasureFn ?NUMBER2 ?UNIT)) (MeasureFn ?VALUE ?UNIT)))))` has axiom `(=> (and (instance ?REL RelationExtendedToQuantities) (instance ?REL BinaryRelation) (instance ?NUMBER1 RealNumber) (instance ?NUMBER2 RealNumber) (holds ?REL ?NUMBER1 ?NUMBER2)) (forall (?UNIT) (=> (instance ?UNIT UnitOfMeasure) (holds ?REL (MeasureFn ?NUMBER1 ?UNIT) (MeasureFn ?NUMBER2 ?UNIT)))))` is second domain of MeasureFn PhysicalQuantity is partitioned into ConstantQuantity, FunctionQuantity Abstract is disjoint from Physical 