Let, \(v\) be velocity of the satellite
Now, for the satellite to revolve in the orbit the centripetal force must be balanced by gravitational force i.e.,
\(F_{c}=F_{g} \rightarrow(1)\)
we know that,
\(F_{c}=\frac{m v^{2}}{r}\) and \(F_{g}=G M m r^{2}\)
substituting these values in \((1)\)
\(\frac{m v^{2}}{r}=\frac{G M m}{r^{2}}\)
After solving this equation we get
\(v^{2}=\frac{G M}{r}\)