Question

Quantas diagonais possui um, pentadecagono e um poligono de 18 lados

Answer 1

Resposta:

Explicação passo-a-passo:

$D_{n}=\frac{n.(n-3)}{2}\\D_{15}=\frac{15.(15-3)}{2}\\D_{15}=\frac{15.12}{2}\\D_{15}=90\ diagonais\\\\D_{n}=\frac{n.(n-3)}{2}\\D_{18}=\frac{18.(18-3)}{2}\\D_{18}=\frac{18.15}{2}\\D_{18}=135\ diagonais$