[tex]\large\boxed{\begin{array}{l} \rm{S_i = (n - 2) \cdot180 {}^{ \circ} } \\ \rm{S_i = (3 - 2) \cdot180 {}^{ \circ} } \\ \rm{S_i = 1 \cdot180 {}^{ \circ} } \\ \rm{S_i = 180 {}^{ \circ} } \\ \huge\boxed{ \boxed{ \boxed{ \boxed{ \rm \dagger \red{ \maltese}~ \blue{alternativa~C}}}}}\end{array}}[/tex]
