Actually, when you know 2 sides and an included angle, you use the Law of Cosines. (and we don't know if theta is an included angle). Solving for side c c^2 = a^2 + b^2 -2ab * cos(C) c^2 = 36 + 16 - 2*6*4 * cos(60) c^2 = 52 -48*.5 c^2 = 28 c = 5.2915
Using the Law of Sines side c / sin(C) = side b / sin (B) 5.2915 / sin(60) = 4 / sin (B) sin(B) = sin(60) * 4 / 5.2915 sin(B) = 0.86603 * 4 / 5.2915 <span><span>sin(B) = 3.46412
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/ 5.2915 </span>
<span><span><span>sin(B) = 0.6546571451
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Angle B = 40.894 Degrees
sin (A) / side a = sin (B) / side b sin (A) = 6 * sin (40.894) / 4 sin (A) = 6 * 0.65466 / 4 sin (A) = .98199 angle A = 79.109 Degrees
