The solution is being the area enclosed by the circle .
I made the intersection between the sphere and the plane and got:
I know the area of this ellipse, but what is the area of this ellipse projected on the xy plane?
If I knew this could substitute an got the value:
I think you meant 'sphere'.
But the problem is that the intersection between the sphere and the plane give us the ellipse that I wrote in the first post.
The area of this ellipse multiply by -3 is = = .
But the answer is .
Shouldn't I project this area on the xy plane?