Four Fours/Lemmata/Three Fours/9/Solutions/2

Puzzle: Three Fours: $9$

Using exactly $3$ instances of the number $4$, the task is to write an expression for $9$, using whatever arithmetical operations you consider necessary.

Solution

$9 = \paren {\sqrt {\dfrac 4 {. \dot 4} } }^{\sqrt 4}$