6 less than n is greater than 8​

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?

The sales totals at macy's food store have increased exponentially over the months. which of these best shows the sales in the first three months?

This is about circle theorems. someone asap : (