Question

d=n.(n -3)
_______
2
Quantas diagonais tem um octógono?

Answer 1

Resposta:

20 espero ter ajudado .....

Answer 2

fórmula:

$\Large\boxed{\begin{array}{l} \Large\boxed{\begin{array}{l} \sf{d = \dfrac{n \cdot(n - 3)}{2} }\end{array}}\end{array}}$

Cálculos:

$\Large\boxed{\begin{array}{l} \Large\boxed{\begin{array}{l} \sf{d = \dfrac{ n \cdot(n - 3) }{2} } \\ \\ \sf{d = \dfrac{8 \cdot(8 - 3)}{2} } \\ \\ \sf{d = \dfrac{8 \cdot5}{2} } \\ \\ \sf{d = \dfrac{40}{2} } \\ \\ \boxed{ \boxed{ \sf{d = 20}}} \checkmark\end{array}}\end{array}}$