# The calculator of the nine-sided

Calculation of a nine-polygon (a figure with nine vertices). Enter one known value, then click calculate.

.**The calculator of the nine-polygon, enter one known value**

**Side length (a)**

**Smaller diagonal (d1)**

**The middle diagonal (e)**

**Large diagonal (d3)**

**Height (h)**

**Perimeter (p)**

**Square (S)**

**The radius of the circumscribed circle (R)**

**Radius of the inscribed circle (r)**

## Formulas:

a = 2 * R * sin( π / 9 )

d = 2 * R * sin( 2 * π / 9 )

e = 2 * R * sin( 3 * π / 9 )

f = 2 * R * sin( 4 * π / 9 )

h = R + r

p = 9 * a

S = 9/2 * R * sin( 2 * π / 9 )

r = a / 2 * tan( π / 9 )

Angle: 140°, 27 diagonals.