Determine the links ANB given the following information

In simplified exponential notation, the expression a^2•a^-3•a 1/a 0

1- what do you think the product of a nonzero rational number and an irrational number is? is it rational or irrational? make use of variables, the closure property of integers, and possibly a proof by contradiction to prove your hypothesis.2- why do we have to specify that the rational number must be nonzero when we determine what the product of a nonzero rational number and an irrational number is? if the rational number were 0, would it give us the same result we found in the first question?

Tan198=asin164=? how to solve this? ?