[tex] \cup [/tex] gives is union

[tex] \cap [/tex] gives is intersection

[tex] \subseteq [/tex] gives is subset

[tex] \in [/tex] gives is element

[tex] \emptyset [/tex] gives is emptyset

[tex] \wedge [/tex] gives is or

[tex] \vee [/tex] gives is and

[tex] \sqrt{x+1} [/tex] gives

Those are just a few examples. Go here.