a) At what values of t does the graph of y = tan t have vertical asymptotes? What can you say about the graph of y = cos t at the same values of t?

b) At what values of t does the graph of y = tan t have t-intercepts? What can you say about the graph of y = sin t at the same values of t?

I have already graphed the tan function and it keeps repeating itself in many periods and so it has many asymptotes. But I am confused as to which values of t do I choose from? Please explain how to get the answer for these. Thank you.