x^2 + y^2<=(abs(z) - a)^2 and x>=0 and -a<=z<=a or x^2 + z^2<=(abs(y) - a)^2 and x<=0 and -a<=y<=a

S = 2 sqrt(2) π a^2

x^_ = (0, 0, 0)

V = (2 π a^3)/3

I = (a^2/4 | 0 | 0 0 | (11 a^2)/40 | 0 0 | 0 | (11 a^2)/40)

2 a

χ = 1

convex solids