Question

Tick (✓) the correct answer:
How many diagonals are there in a pentagon?
(a) 5
(b) 7
(c) 6
(d) 10

Answer 1

(a) 5

For a pentagon:
$n=5$

$\mathrm{Number}\mathrm{of}\mathrm{diagonals}=\frac{n\left(n-3\right)}{2}=\frac{5\left(5-3\right)}{2}=5$