${\displaystyle \underset{\_<!--\; \_\; -->}{\text{Some useful trig formulae}}}$



${\displaystyle \text{Law of Sines}}$

${\displaystyle \frac{a}{sin(A)}=\frac{b}{sin(B)}=\frac{c}{sin(C)}=\frac{abc}{2\cdot <!--\; \cdot \; -->Area}=2R}$



${\displaystyle \text{Law of Cosines}}$

${\displaystyle c^2=a^2+b^2-<!--\; -\; -->2ab\cdot <!--\; \cdot \; -->cos(C)}$



${\displaystyle \text{Law of Cotangents}}$

${\displaystyle \frac{cot(\frac{A}{2})}{s-<!--\; -\; -->a}=\frac{cot(\frac{B}{2})}{s-<!--\; -\; -->b}=\frac{cot(\frac{C}{2})}{s-<!--\; -\; -->c}=\frac{1}{r}}$



${\displaystyle \text{Heron's Formula}}$

${\displaystyle Area=\sqrt{s(s-<!--\; -\; -->a)(s-<!--\; -\; -->b)(s-<!--\; -\; -->c)}}$



${\displaystyle \text{Star Trek Lemma}}$