Given a triangle with a = 9, b = 11, a = 31°, what is (are) the possible length(s) of c? round your answer to two decimal places. a) 16.42 or 2.44 b) 6.61 c) 14.21 d) 16.42 or 3.41

You can use the Law of Cosines to figure this.
  a² = b² +c² -2bc×cos(A)
  c² -(2b×cos(A))c +b² -a² = 0
  c² -18.8577c +40 = 0 . . . . . . . substituting the given values
Then we can use the quadratic formula to find c.
  c = (18.8577 ±√(18.8577² -160))/2
  c = (18.8577 ±13.9861)/2 ≈ {2.44, 16.42}

The appropriate choice is ...
  A) 16.42 or 2.44

19/91

Step-by-step explanation:

In total, there are 91 combinations of student preferences and reading amounts. Out of these, 19 read about three hours a week of paperback books. 19/91 cannot be simplified, so it is the final answer. Hope this helps!