パラメータ 結果 a b c A B C = = = = = = a b c A B C = = = = = =

 $$a=\sqrt{b^{2}+c^{2}-2bc\cos{A}}$$ $$b=\sqrt{c^{2}+a^{2}-2ca\cos{B}}$$ $$c=\sqrt{a^{2}+b^{2}-2ab\cos{C}}$$ $$A=\cos^{-1}{\frac{b^{2}+c^{2}-a^{2}}{2bc}}$$ $$B=\cos^{-1}{\frac{c^{2}+a^{2}-b^{2}}{2ca}}$$ $$C=\cos^{-1}{\frac{a^{2}+b^{2}-c^{2}}{2ab}}$$