Knowing two legs of the triangle, 6 and , we know that this is a 30-60-90 triangle since the measurements match the requirements. Therefore, the last angle is 30 degrees.
SOH,CAH, TOA so it would be TANGENT since it would be Opposite over Adjacent. Tan(15) = 9/a put Tan(15) onto your calculator it would be .267949 round that to .27 = 9/a cross multiply a = 33.588. C is the correct answer.