[tex]\begin{array}{llll} \textit{sum of all interior}\\ \textit{angles in a regular polygon} \end{array}\\\\ n\theta = 180(n-2)~~ \begin{cases} n=\stackrel{number~of}{sides}\\ \theta =\stackrel{degrees}{angle}\\[-0.5em] \hrulefill\\ n=19 \end{cases}\implies 19\theta =180(19-2) \\\\\\ 19\theta =180(17)\implies 19\theta =3060\implies \theta =\cfrac{3060}{19}\implies \theta \approx 161.1^o[/tex]