\[\boxed{\mathbf{219}\mathbf{.}}\]
\[1)\ OK = 7 \cdot 3 = 21\ см;\]
\[MK = OK - OM = 21 - 7 =\]
\[= 14\ см.\]
\[2)\ OK = 7 \cdot 3 = 21\ см.\]
\[MK = OK + OM = 7 + 21 =\]
\[= 28\ см.\]