Question

Calcular o número de diagonais do octógono

Answer 1

Boa Noooite.. Usamos a fórmula.

d = N.(n-3)/2
d = 8*(8-3)/2
d = 4*5
d = 20 diagonais.

Answer 2

$\large\boxed{\begin{array}{l} \rm \: d = \dfrac{n \: . \: (n - 3)}{2} \\ \\ \rm \: d = \dfrac{8 \: . \:(8 - 3) }{2} \\ \\ \rm \: d = \dfrac{8 \: . \: 5}{2} \\ \\ \rm \: d = \dfrac{40}{2} \\ \\ \boxed{ \boxed{ \rm{d = 20}}}\end{array}}$