Question

calcule a soma dos angulos internos dos poligonos
eneágono(9 lados)

Answer 1

Sn=180(n-2)
Sn=180(9-2)
Sn= 180*7
Sn= 1260

Answer 2

$\large\displaystyle\boxed{\begin{array}{l}\sf{\displaystyle{\sf{S_i = (n - 2)\cdot180 {}^{ \circ} }}} \\ \\ \sf{S_i = (9 - 2) \cdot180 {}^{ \circ} } \\ \\ \sf{S_i = 7 \cdot180 {}^{ \circ} } \\ \\ \boxed{ \boxed{ \sf{S_i = 1260 {}^{ \circ} }}}\end{array}}$