You need the Law of Cosines here, since you only have 1 angle measure. If you had 2 you could use the Law of Sines, but nevertheless, we'll get there. The Law of Cosines for our particular set of info looks like this: [tex]x^2=65^2+41^2-2(65)(41)cos(35)[/tex]. Simplifying a bit we get [tex]x^2=4225+1681-4366.080396[/tex] and [tex]x^2=1539.9196[/tex]. Taking the square root of that and considering the principle root only, x = 39.2, second choice down.
