Help mebin these questions (Chapter - MENSURATION)​

Which of the following is most likely the next step in the series? a3z, b6y, c9x, d12w, е15v, f18u

If two parallel lines are cut by a transversal, interior angles on the same side of the transversal are supplementary. a. always b. sometimes c. never

In triangle abc, angle c is a right angle. find the value of the trig function indicated. find tan a if c = 17 and a = 8