Geometry & Trigonometry
Intermediate

Number of Diagonals

Count of diagonals in an n-sided polygon.

Formula

D=n(n−3)2D = \frac{n(n-3)}{2}

Variables

nSides

Example

Hexagon has 9 diagonals

Did You Know?

A polygon with n sides has n(n−3)/2 diagonals, so a humble decagon already hides 35 of them.

polygon