For this case we have that by definition, the surface area of a sphere is given by:
[tex]SA = 4 * \pi * r ^ 2[/tex]
They tell us as data that the surface area of the sphere is 16 \ units ^ 2.
[tex]16 = 4 * \pi * r ^ 2[/tex]
We cleared the radio:
[tex]\frac {16} {4} = \pi * r ^ 2\\4 = \pi * r ^ 2\\\frac {4} {\pi} = r ^ 2\\1,27388535032 = r ^ 2\\r = \pm \sqrt {1,27388535032}[/tex]
We take the positive value, rounding:
[tex]r = 1.13 \ units[/tex]
Answer:
[tex]r = 1.13 \ units[/tex]
