Solution
= Solution
The inclusion $F\subseteq K$ makes $K$ a <vector space> over $F$ by its own addition and multiplication by elements of $F$. The extension is finite when this <vector space> has a finite <basis>. Its <degree of a field extension> is
$$
\boxed{[K:F]=\dim_FK.}
$$
Being a <finite field extension> concerns vector-space dimension, not the cardinality of the underlying field.