Solid Angles

[kerasene]

Hey i'm having a hard time wrapping my head around the concept of solid angles and finding the solid angle of any area on the surface of a sphere i'm basically asking for a crash course none of my textbooks explain it well at all

[mathman]

The most direct way is is the area of the surface patch divided by r2, where r is the radius of the sphere.

[HallsofIvy]

Mathman is correct. That's how the measure of a solid angle is defined- the "solid angle" intecepted by the entire sphere around a point has measure 4\pi, the surface area, 4\pi r^2, divided by r^2.