Amsmath amssymb or mathtools. Unicode now calls the curly epsilon GREEK SMALL LETTER EPSILON e this is a textual Greek letter rather than a math alphabetic symbol and the symbol that TeX traditionally assigns to epsilon is called GREEK LUNATE EPSILON SYMBOL ϵ the symbol being a hint that this is intended as a mathematical character rather than a textual Greek letter. In the menu bar go to.
In the menu bar go to.
Some symbols are quired packages. Note that the formula will appear below your drawing area. This is not a comprehensive list. O O displaystyle oO o O.