Ok, guys.

I am on my first year on Engineering Mechanics and by now I got stuck at this problem:

**A hole of radius r is bored through the center of a sphere of**

radius R > r . Find the volume of the remaining portion of the

sphere.

The reason is that my answer doesn't match with the book's one.

OK, here is what I did:

A picture worths more than 1000 words

I know another way to solve it, and it gives me the right answer. But I can't find any gap at the answer I did above

Thank you for you atention, and Math bless you all.