Square root of 3 over 8 is rational or irrational? why

One expression below in undefined, and the other expression has a well defined value. which expression is undefined and explain why it has no value. which expression is defined? what is the value of that expression and how do you know? what is a different expression using a trig inverse function that is also undefined?

You have 3 boxes, one "strawberries"; one "mentos" and one "mixed".but you know that all the labels are in incorrect order .how do you know witch is witch?

This is different from the first one can someone me