Yg di cari pion C aja

c) x = √(73²+91²-2.73.91.cos 60) = √6967 = 83,47

x/sin 60° = 91/sin C = 73/sin A

x² = AB² + BC² - 2AB.BC.cos B
x² = 91² + 73² - 2.91.73.1/2
x² = 91² + 73² - 91.73
x = 83,47

sin C = 91 sin 60°/x = 0,944
C = arc sin 0,944 = 70,76°

sudut A = 180° - (B + C) = 49,24°