Which trig function would you use to solve this?

For some reason its not letting me link to picture or anything so.

It has a degrees of 18 and a base of 100 meters

As voters exit the polls, you ask a representative random sample of voters if they voted for a proposition. if the true percentage of voters who vote for the proposition is 63%, what is the probability that, in your sample, exactly 5 do not voted for the proposition before 2 voted for the proposition? the probability is