Solución
∬
S
∣
∣
R
∣
∣
R
⋅
n
d
s
=
4
π
a
4
\iint_S ||\bold{R}|| \bold{R}\cdot nds = 4\pi a^4
∬
S
∣∣
R
∣∣
R
⋅
n
d
s
=
4
π
a
4