\text{Loi des sinus} \\ [0.2int]
\frac{a}{\sin{\widehat{A}}} = \frac{b}{\sin{\widehat{B}}} = \frac{c}{\sin{\widehat{C}}}\text{Loi des cosinus} \\ \text{ou} \\ \text{Formule d'Al-Kashi} \\ [0.2int]
\mathrm{a^2 = b^² + c^² - 2bc \cos{ \widehat{A}}} \\[0.2int]
\mathrm{b^2 = a^² + c^² - 2ac \cos{ \widehat{B}}} \\[0.2int]
\mathrm{c^2 = a^² + b^² - 2ab \cos{ \widehat{C}}}