[tex]ab = 12 \\ ac = 12\sqrt{3} \\ ........................ \\ = > {bc}^{2} = {ab}^{2} + {ac}^{2} \\ = > {bc}^{2} = {12}^{2} + { (12\sqrt{3}) }^{2} \\ = > {bc}^{2} = 144 + 144 \times 3 = 144 + 432 = 576 \\ = > bc = \sqrt{576} = 24 \: cm[/tex]
[tex]ab = 12 \\ bc = 24 \\ = > (t \: .30grade) = > m( < \: acb) = 30 \: grade \\ = > m( < abc) = 90 - 30 = 60 \: grade[/tex]
