is this a center of mass question?

[jlmac2001]

Question: Find the solid angle subtended at the origin by a thin circular disk of radius a, whose cente is a distance b from the origin and where the normal to the disk is parallel.

Do I have to find the center of mass to solve this question?

[Tom Mattson]

"is this a center of mass question?"

No, it's a "solid angle" question. [:D]

This question is purely geometrical, and has nothing to do with distriubtion of mass.

[jlmac2001]

how would I do it?