Question

wa

Answer 1

use the law of sins
http://en.wikipedia.org/wiki/Law_of_sines

Answer 2

you set up a ratio of side to angle. side a to angle A = side b to angle B
here we know side a, and we need to figure out angle A (easy to do, angles of a triangle add up to 180). we know angle C. we are looking for side c
\[ \frac{a}{sin(A)} = \frac{c}{sin(17)} \]

Answer 3

angle A= 180 - B -C= 180- 49-17
side a = 5

Answer 4

so your answer is on the right track, but angle A is not 49