Question

Qual a soma dos Ângulos internos de um icosagono ?

Answer 1

Resposta:

icosagono  tem 20 lados

Ai+Ae=180

Ae=360/n=360/20 =18

Ai+18=180

Ai=162º

Si=20 * 162 = 3.240º

ou

use Si=180*n-360 = 180*20-360  = 3.240º‬

Answer 2

$\large\displaystyle\boxed{\begin{array}{l} \sf \: S_i = (n - 2) \cdot180 {}^{ \circ} \\ \\ \sf \: S_i = (20 - 2) \cdot {180}^{ \circ} \\ \\ \sf \: S_i = 18 \cdot180 {}^{ \circ} \\ \\ \boxed{ \boxed{ \sf{S_i = 3240 {}^{ \circ} }}}\end{array}}$