The equation for the surface area of a sphere is [tex]A=4 \pi r^{2} [/tex]
So plug in 3 cm for radius "r"
[tex]A=4 \pi ( 3cm)^{2} [/tex]
Simplify
[tex]A=4 \pi (9 cm^{2})[/tex]
[tex]A=36 \pi cm^{2} [/tex]
Depending on your teacher, they might want you to leave it like this or plug in 3.14 for [tex] \pi [/tex]
So your answer is either
[tex]A=36 \pi cm^{2} [/tex]
or
[tex]A=113.04 cm^{2} [/tex]